WO2025116911A1

WO2025116911A1 - Copper/mixed oxide catalysts for isobutanol synthesis; their preparations and butanol synthesis method by alcohol condensation over said catalysts

Info

Publication number: WO2025116911A1
Application number: PCT/US2023/081865
Authority: WO
Inventors: Desmond SCHIPPER; Richard Long
Original assignee: China Petroleum and Chemical Corp; UOP LLC
Current assignee: China Petroleum and Chemical Corp; Honeywell UOP LLC
Priority date: 2023-11-30
Filing date: 2023-11-30
Publication date: 2025-06-05
Anticipated expiration: 2026-05-30

Abstract

Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺ oxide catalysts have been developed for use in producing isobutanol in propanol-methanol, ethanol-methanol and propanol/ethanol mixture-methanol Guerbet reactions. The catal sts can also be used in makin n-butanol in ethanol-ethanol reactions. The Cu/M²⁺ M³⁺ oxide or CuO/M² M³ oxide catalyst has an average Cu or CuO particle size greater than or equal to 20 nm. M²⁺ may comprise divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof. M³⁺ may comprise trivalent aluminum, gallium, chromium, or combinations thereof. Catalysts, methods of making the catalysts, and methods of using the catalysts are described.

Description

CATALYSTS FOR ISOBUTANOL SYNTHESIS BACKGROUND [0001] Isobutanol is an organic solvent and a feedstock in the manufacturing of isobutyl acetate and isobutyl esters. It can also be blended directly with gasoline to improve octane number and combustion efficiency or be used neat as an alternative fuel. Isobutanol has relatively higher energy density and lower volatility compared to ethanol. In addition, it does not readily absorb water from air, preventing or reducing the corrosion of engines and pipelines. Although isobutanol has many potential uses, its synthesis is limited. Isobutanol is currently produced through the carbonylation of propylene. This process involves reacting propylene with carbon monoxide and hydrogen to generate butyraldehyde and isobutyraldehyde, hydrogenating them to n-butanol and isobutanol, followed by separation of the butanols. A new alternative technology is biomass fermentation. However, isobutanol selectivities in these two homogeneous processes are low, and the productivities are limited, resulting in a high cost of isobutanol. [0002] Guerbet reaction is an alternative process for isobutanol synthesis from methanol and ethanol/propanol. This reaction is of special importance because it can produce value added isobutanol from the low-cost mixed alcohols. The Guerbet reaction takes place by a coupling process between alcohols on multi-functional catalysts with dehydrogenation activity, strong surface basicity, mild acidity, and hydrogenation activity. The reactions are below: C2H5OH + CH3OH = C3H7OH + H2O (1) C3H7OH + CH3OH = C4H9OH + H2O (2) C2H5OH + 2CH3OH = C4H9OH + 2H2O (3) [0003] As a result, various catalysts and processes for producing isobutanol from methanol, ethanol and propanol have been sought. For example, US Patents Nos. 5,581,602, 5,707,920, 5,770,541, 5,908,807, 5,939,352 and 6,034,141 describe precious metal loaded alkali metal doped ZnMnZr oxide catalysts for converting methanol and ethanol, or methanol, ethanol and propanol to isobutanol. [0004] US 5,559,275 discloses a process for the conversion of methanol, ethanol and propanol to higher branched oxygenates, such as isobutanol on a catalyst comprising a) a mixed oxide support having at least two components selected from Zn, Mg, Zr, Mn, Ti, Cr and La oxides; and b) an active metal selected from Pd, Pt, Ag, Rh, Co, and mixtures thereof. [0005] Carlini, “Guerbet condensation of methanol with n-propanol to isobutyl alcohol over heterogeneous bifunctional catalysts based on Mg-Al mixed oxides partially substituted by different metal components, ” Journal of Molecular Catalysis A: Chemical, 2005, 232, 13, describes Pd, Rh, Ni and Cu doped on Mg-Al mixed oxides for isobutanol synthesis from methanol and propanol. [0006] US 20190031585 discloses a method of converting ethanol to higher alcohols (such as n-butanol) on Cu-MgO-Al₂O₃ catalyst having less than 0.25 wt% Cu. The Cu is a pseudo-single-atom and it is small and highly dispersed on the support. [0007] Gabriëls, “Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization,” Catalysis Science & Technology, 2015, 5, 3876, summarizes a series of catalysts for the reaction between methanol and ethanol/propanol, including alkali or alkaline earth supported on Al₂O₃, Ca or Sr hydroxyapatite, hydrotalcite, MgO, Mg(OH)2, Rb-Li exchanged zeolite X and Na2CO3/NaX. [0008] There remains a need for catalysts producing isobutanol from methanol, ethanol, and propanol, and for methods of making and using the catalysts. DETAILED DESCRIPTION [0009] Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalysts have been developed which exhibit good isobutanol yield in propanol-methanol, ethanol-methanol and propanol/ethanol mixture-methanol reactions. They also exhibit good n-butanol yield in ethanol-ethanol reactions. Methanol and ethanol can be reacted to form propanol, which can then react with methanol to form isobutanol using the Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalysts. Alternatively, methanol and propanol can be reacted directly to produce isobutanol using the Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalysts. Mixtures of propanol and ethanol can be reacted with methanol. Ethanol can also be reacted with ethanol to form n-butanol. [0010] The invention involves a pre-treatment process in which the alcohol condensation (Guerbet) catalyst, which is initially comprised of CuO and other components such as MgO-Al₂O₃, is contacted with a solvent, such as water, alcohols, aldehydes, ketones, ethers, esters, polyols, hydrocarbons, or combinations thereof. Crystalline copper with larger size is observed to form at mild temperatures (e.g., 170°C). The increased crystallite size, as well as its distribution within the catalyst, leads to a significant improvement in performance. [0011] One aspect of the invention is an alcohol condensation catalyst for the synthesis of isobutanol. In one embodiment, the catalyst comprises a Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst. M²⁺ may comprise divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof. M²⁺ may consist essentially of divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof. M²⁺ may be selected from the group consisting of divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof. M³⁺ may comprise trivalent aluminum, gallium, chromium, or combinations thereof. M³⁺ may consist essentially of trivalent aluminum, gallium, chromium, or combinations thereof. M³⁺ may be selected from the group consisting of trivalent aluminum, gallium, chromium, or combinations thereof. [0012] The Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺oxide catalyst has average Cu or CuO particle size greater than or equal to 20 nm, or greater than or equal to 30 nm, or greater than or equal to 40 nm, or greater than or equal to 50 nm, or greater than or equal to 60 nm, or greater than or equal to 70 nm, or greater than or equal to 80 nm, or greater than or equal to 90 nm, or greater than or equal to 100 nm, or greater than or equal to 150 nm, or greater than or equal to 200 nm, or greater than or equal to 250 nm, or greater than or equal to 300 nm, or greater than or equal to 350 nm, or greater than or equal to 400 nm, or in a range of 20 nm to 5000 nm, or 20 nm to 4000 nm, or 20 nm to 3000 nm, or 20 nm to 2000 nm, or 20 nm to 1750 nm, or 20 nm to 1500 nm, or 20 nm to 1250 nm, or 20 nm to 1000 nm, or 20 nm to 900 nm, or 20 nm to 800 nm, or 20 nm to 700 nm, or 20 nm to 600 nm, or 20 nm to 500 nm, or 30 nm to 5000 nm, or 30 nm to 4000 nm, or 30 nm to 3000 nm, or 30 nm to 2000 nm, or 30 nm to 1750 nm, or 30 nm to 1500 nm, or 30 nm to 1250 nm, or 30 nm to 1000 nm, or 30 nm to 900 nm, or 30 nm to 800 nm, or 30 nm to 700 nm, or 30 nm to 600 nm, or 30 nm to 500 nm, or 40 nm to 5000 nm, or 40 nm to 4000 nm, or 40 nm to 3000 nm, or 40 nm to 2000 nm, or 40 nm to 1750 nm, or 40 nm to 1500 nm, or 40 nm to 1250 nm, or 40 nm to 1000 nm, or 40 nm to 900 nm, or 40 nm to 800 nm, or 40 nm to 700 nm, or 40 nm to 600 nm, or 40 nm to 500 nm, or 50 nm to 5000 nm, or 50 nm to 4000 nm, or 50 nm to 3000 nm, or 50 nm to 2000 nm, or 50 nm to 1750 nm, or 50 nm to 1500 nm, or 50 nm to 1250 nm, or 50 nm to 1000 nm, or 50 nm to 900 nm, or 50 nm to 800 nm, or 50 nm to 700 nm, or 50 nm to 600 nm, or 50 nm to 500 nm, or 60 nm to 5000 nm, or 60 nm to 4000 nm, or 60 nm to 3000 nm, or 60 nm to 2000 nm, or 60 nm to 1750 nm, or 60 nm to 1500 nm, or 60 nm to 1250 nm, or 60 nm to 1000 nm, or 60 nm to 900 nm, or 60 nm to 800 nm, or 60 nm to 700 nm, or 60 nm to 600 nm, or 60 nm to 500 nm, or 80 nm to 5000 nm, or 80 nm to 4000 nm, or 80 nm to 3000 nm, or 80 nm to 2000 nm, or 80 nm to 1750 nm, or 80 nm to 1500 nm, or 80 nm to 1250 nm, or 80 nm to 1000 nm, or 80 nm to 900 nm, or 80 nm to 800 nm, or 80 nm to 700 nm, or 80 nm to 600 nm, or 80 nm to 500 nm, or 100 nm to 5000 nm, or 100 nm to 4000 nm, or 100 nm to 3000 nm, or 100 nm to 2000 nm, or 100 nm to 1750 nm, or 100 nm to 1500 nm, or 100 nm to 1250 nm, or 100 nm to 1000 nm, or 100 nm to 900 nm, or 100 nm to 800 nm, or 100 nm to 700 nm, or 100 nm to 600 nm, or 100 nm to 500 nm, 200 nm to 5000 nm, or 200 nm to 4000 nm, or 200 nm to 3000 nm, or 200 nm to 2000 nm, or 200 nm to 1750 nm, or 200 nm to 1500 nm, or 200 nm to 1250 nm, or 200 nm to 1000 nm, or 200 nm to 900 nm, or 200 nm to 800 nm, or 200 nm to 700 nm, or 200 nm to 600 nm, or 200 nm to 500 nm, or 300 nm to 5000 nm, or 300 nm to 4000 nm, or 300 nm to 3000 nm, or 300 nm to 2000 nm, or 300 nm to 1750 nm, or 300 nm to 1500 nm, or 300 nm to 1250 nm, or 300 nm to 1000 nm, or 300 nm to 900 nm, or 300 nm to 800 nm, or 300 nm to 700 nm, or 300 nm to 600 nm, or 300 nm to 500 nm, or 400 nm to 5000 nm, or 400 nm to 4000 nm, or 400 nm to 3000 nm, or 400 nm to 2000 nm, or 400 nm to 1750 nm, or 400 nm to 1500 nm, or 400 nm to 1250 nm, or 400 nm to 1000 nm, or 400 nm to 900 nm, or 400 nm to 800 nm, or 400 nm to 700 nm, or 400 nm to 600 nm, or 400 nm to 500 nm. [0013] In some embodiments, the Cu or CuO is present in the catalyst in an amount of 0.5 wt% to 75 wt%, or 0.5 wt% to 50 wt%, or 0.5 wt% to 30 wt%, or 0.5 wt% to 20 wt%, or 1 wt% to 75 wt%, or 1 wt% to 50 wt%, or 1 wt% to 30 wt%, or 1 wt% to 20 wt%, or 2 wt% to 75 wt%, or 2 wt% to 50 wt%, or 2 wt% to 30 wt%, or 2 wt% to 20 wt%, or 5 wt% to 75 wt%, or 5 wt% to 50 wt%, or 5 wt% to 30 wt%, or 5 wt% to 20 wt% or 10 wt% to 75 wt%, or 10 wt% to 50 wt%, or 10 wt% to 30 wt%, or 10 wt% to 20 wt%, or 15 wt% to 75 wt%, or 15 wt% to 50 wt%, or 15 wt% to 30 wt%, or 15 wt% to 20 wt%. [0014] In some embodiments, M²⁺O is present in the catalyst in an amount of 1 wt% to 98 wt%, or 1 wt% to 75 wt%, or 1 wt% to 70 wt%, or 1 wt% to 65 wt%, or 1 wt% to 60 wt%, or 2 wt% to 98 wt%, or 2 wt% to 75 wt%, or 2 wt% to 70 wt%, or 2 wt% to 65 wt%, or 2 wt% to 60 wt%, or 5 wt% to 98 wt%, or 5 wt% to 75 wt%, or 5 wt% to 70 wt%, or 5 wt% to 65 wt%, or 5 wt% to 60 wt%, or 10 wt% to 98 wt%, or 10 wt% to 75 wt%, or 10 wt% to 70 wt%, or 10 wt% to 65 wt%, or 10 wt% to 60 wt%, or 15 wt% to 98 wt%, or 15 wt% to 75 wt%, or 15 wt% to 70 wt%, or 15 wt% to 65 wt%, or 15 wt% to 60 wt%, or 20 wt% to 98 wt%, or 20 wt% to 75 wt%, or 20 wt% to 70 wt%, or 20 wt% to 65 wt%, or 20 wt% to 60 wt%, or 25 wt% to 98 wt%, or 25 wt% to 75 wt%, or 25 wt% to 70 wt%, or 25 wt% to 65 wt%, or 25 wt% to 60 wt%, or 30 wt% to 98 wt%, or 30 wt% to 75 wt%, or 30 wt% to 70 wt%, or 30 wt% to 65 wt%, or 30 wt% to 60 wt%, or 35 wt% to 98 wt%, or 35 wt% to 75 wt%, or 35 wt% to 70 wt%, or 35 wt% to 65 wt%, or 35 wt% to 60 wt%, or, 40 wt% to 98 wt%, or 40 wt% to 75 wt%, or 40 wt% to 70 wt%, or 40 wt% to 65 wt%, or 40 wt% to 60 wt%, or 45 wt% to 98 wt%, or 45 wt% to 75 wt%, or 45 wt% to 70 wt%, or 45 wt% to 65 wt%, or 45 wt% to 60 wt%, or 50 wt% to 98 wt%, or 50 wt% to 75 wt%, or 50 wt% to 70 wt%, or 50 wt% to 65 wt%, or 50 wt% to 60 wt%, or 55 wt% to 98 wt%, or 55 wt% to 75 wt%, or 55 wt% to 70 wt%, or 55 wt% to 65 wt%, or 55 wt% to 60 wt%5 wt% to 98 wt%, or 5 wt% to 75 wt%, or 5 wt% to 70 wt%, or 5 wt% to 65 wt%, or 5 wt% to 60 wt%, or 10 wt% to 98 wt%, or 10 wt% to 75 wt%, or 10 wt% to 70 wt%, or 10 wt% to 65 wt%, or 10 wt% to 60 wt%, or 15 wt% to 98 wt%, or 15 wt% to 75 wt%, or 15 wt% to 70 wt%, or 15 wt% to 65 wt%, or 15 wt% to 60 wt%, or 20 wt% to 98 wt%, or 20 wt% to 75 wt%, or 20 wt% to 70 wt%, or 20 wt% to 65 wt%, or 20 wt% to 60 wt%, or 25 wt% to 98 wt%, or 25 wt% to 75 wt%, or 25 wt% to 70 wt%, or 25 wt% to 65 wt%, or 25 wt% to 60 wt%, or 30 wt% to 98 wt%, or 30 wt% to 75 wt%, or 30 wt% to 70 wt%, or 30 wt% to 65 wt%, or 30 wt% to 60 wt%, or 35 wt% to 98 wt%, or 35 wt% to 75 wt%, or 35 wt% to 70 wt%, or 35 wt% to 65 wt%, or 35 wt% to 60 wt%, or, 40 wt% to 98 wt%, or 40 wt% to 75 wt%, or 40 wt% to 70 wt%, or 40 wt% to 65 wt%, or 40 wt% to 60 wt%, or 45 wt% to 98 wt%, or 45 wt% to 75 wt%, or 45 wt% to 70 wt%, or 45 wt% to 65 wt%, or 45 wt% to 60 wt%, or 50 wt% to 98 wt%, or 50 wt% to 75 wt%, or 50 wt% to 70 wt%, or 50 wt% to 65 wt%, or 50 wt% to 60 wt%, or 55 wt% to 98 wt%, or 55 wt% to 75 wt%, or 55 wt% to 70 wt%, or 55 wt% to 65 wt%, or 55 wt% to 60 wt%. [0015] In some embodiments, M³⁺ 2O₃ is present in the catalyst in an amount of 1 wt% to 98 wt%, or 1 wt% to 75 wt%, or 1 wt% to 70 wt%, or 1 wt% to 65 wt%, or 1 wt% to 60 wt%, or 2 wt% to 98 wt%, or 2 wt% to 75 wt%, or 2 wt% to 70 wt%, or 2 wt% to 65 wt%, or 2 wt% to 60 wt%, or 5 wt% to 98 wt%, or 5 wt% to 75 wt%, or 5 wt% to 70 wt%, or 5 wt% to 65 wt%, or 5 wt% to 60 wt%, or 10 wt% to 98 wt%, or 10 wt% to 75 wt%, or 10 wt% to 70 wt%, or 10 wt% to 65 wt%, or 10 wt% to 60 wt%, or 15 wt% to 98 wt%, or 15 wt% to 75 wt%, or 15 wt% to 70 wt%, or 15 wt% to 65 wt%, or 15 wt% to 60 wt%, or 20 wt% to 98 wt%, or 20 wt% to 75 wt%, or 20 wt% to 70 wt%, or 20 wt% to 65 wt%, or 20 wt% to 60 wt%, or 25 wt% to 98 wt%, or 25 wt% to 75 wt%, or 25 wt% to 70 wt%, or 25 wt% to 65 wt%, or 25 wt% to 60 wt%, or 30 wt% to 98 wt%, or 30 wt% to 75 wt%, or 30 wt% to 70 wt%, or 30 wt% to 65 wt%, or 30 wt% to 60 wt%, or 35 wt% to 98 wt%, or 35 wt% to 75 wt%, or 35 wt% to 70 wt%, or 35 wt% to 65 wt%, or 35 wt% to 60 wt%, or, 40 wt% to 98 wt%, or 40 wt% to 75 wt%, or 40 wt% to 70 wt%, or 40 wt% to 65 wt%, or 40 wt% to 60 wt%, or 45 wt% to 98 wt%, or 45 wt% to 75 wt%, or 45 wt% to 70 wt%, or 45 wt% to 65 wt%, or 45 wt% to 60 wt%, or 50 wt% to 98 wt%, or 50 wt% to 75 wt%, or 50 wt% to 70 wt%, or 50 wt% to 65 wt%, or 50 wt% to 60 wt%, or 55 wt% to 98 wt%, or 55 wt% to 75 wt%, or 55 wt% to 70 wt%, or 55 wt% to 65 wt%, or 55 wt% to 60 wt%. [0016] In some embodiments, M²⁺ is divalent magnesium and M³⁺ is trivalent aluminum. [0017] In some embodiments, M²⁺ is divalent magnesium and M³⁺ is trivalent gallium. [0018] In some embodiments, the average Cu or CuO particle size is in the range of 50 nm to 500 nm; Cu or CuO is present in an amount of 2 wt% to 30 wt%; M²⁺ is present as M²⁺O in an amount of 5 wt% to 75 wt%; and M³⁺ is present as M³⁺2O3 in an amount of 5 wt% to 75 wt%. In some embodiments, Cu or CuO is present in an amount of 5 wt% to 20 wt%; M²⁺O is present in an amount of 30 wt% to 60 wt%; and M³⁺2O3 is present in an amount of 30 wt% to 60 wt%. [0019] In some embodiments, M²⁺ is divalent magnesium, and M³⁺ is trivalent aluminum or trivalent gallium. [0020] Another aspect of the invention is method of making an alcohol condensation catalyst for the synthesis of isobutanol. In one embodiment, the pre-treatment involves contacting the catalyst with a solvent and heating to a temperature for a time sufficient to form a pre-treated catalyst having an average Cu particle size in a range of 20 nm to 5000 nm. The catalyst is then separated from the mixture and dried to provide the highly active pre-treated catalyst. [0021] The temperature is typically in the range of 100°C to 300°C, or 100°C to 275°C, or 100°C to 250°C, or 100°C to 225°C, or 100°C to 200°C, or 100°C to 175°C, or 125°C to 300°C, or 125°C to 275°C, or 125°C to 250°C, or 125°C to 225°C, or 125°C to 200°C, or 125°C to 175°C, 150°C to 300°C, or 150°C to 275°C, or 150°C to 250°C, or 150°C to 225°C, or 150°C to 200°C, or 150°C to 175°C, 175°C to 300°C, or 175°C to 275°C, or 175°C to 250°C, or 175°C to 225°C, or 175°C to 200°C. [0022] The time is typically in the range of 1 to 50 hr, or 1 to 45 hr, or 1 to 40 hr, or 1 to 35 hr, or 1 to 30 hr, or 1 to 25 hr, or 2 to 50 hr, or 2 to 45 hr, or 2 to 40 hr, or 2 to 35 hr, or 2 to 30 hr, or 2 to 25 hr, or 4 to 50 hr, or 4 to 45 hr, or 4 to 40 hr, or 4 to 35 hr, or 4 to 30 hr, or 4 to 25 hr, or 6 to 50 hr, or 6 to 45 hr, or 6 to 40 hr, or 6 to 35 hr, or 6 to 30 hr, or 6 to 25 hr. [0023] The pressure is typically the autogenous pressure of the solvents. In some embodiments, the pressure is in the range of 100 kPa to 10 MPa. [0024] Suitable solvents include, but are not limited to, water, organic solvents including, but not limited to, alcohols, aldehydes, ketones, ethers, esters, polyols, hydrocarbons, or combinations thereof. Suitable alcohols include, but are not limited to, methanol, ethanol, propanols, butanols, pentanols, hexanols, or combinations thereof. The alcohols can be linear or branched. [0025] Optionally, the reactor headspace can be flushed with an inert gas before heating. Suitable inert gases include, but are not limited to N2, Ar, He, and the like. Alternatively, the catalyst could be contacted with a mixture of solvent and inert gas and heated. [0026] The pretreatment can be a batch process or a continuous process. [0027] The Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst can be prepared using any suitable method, including, but not limited to, co-precipitation, deposition- precipitation, impregnation, and/or sol-gel processes. [0028] Alternatively, the method of making the alcohol condensation catalyst may comprise: providing Cu or CuO particles having an average Cu or CuO particle size in a range of 20 nm to 5000 nm; and depositing M²⁺M³⁺oxide on the Cu or CuO particles to form the Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst. M²⁺ may comprise divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof. M³⁺ may comprise trivalent aluminum, gallium, chromium, or combinations thereof. [0029] The M²⁺M³⁺oxide may be deposited using any suitable process, including, but not limited to co-precipitation, deposition-precipitation, impregnation, and/or sol-gel processes. [0030] The Cu or CuO, M²⁺, and M³⁺ may be present in the amounts discussed above. [0031] In some embodiments, M²⁺ is divalent magnesium and M³⁺ is trivalent aluminum or trivalent gallium. [0032] Another aspect of the invention is a method of producing isobutanol or n-butanol. In one embodiment, the method comprises: reacting ethanol or propanol with methanol in the presence of an alcohol condensation catalyst under reaction conditions to produce isobutanol or reacting ethanol with ethanol in the presence of an alcohol condensation catalyst under reaction conditions to produce n-butanol; wherein the alcohol condensation catalyst comprises a Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺ oxide catalyst; wherein M²⁺ comprises divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof; wherein M³⁺ comprises trivalent aluminum, gallium, chromium, or combinations thereof; and wherein the Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺ oxide catalyst has an average Cu particle size in a range of 20 nm to 5000 nm. [0033] In some embodiments, the reaction conditions comprise one or more of: a temperature in a range of 100°C to 500°C; or a pressure in a range of 5 kPa to 30,000 kPa. EXAMPLES [0034] Example 1: Cu_0.1Mg_1.9AlO_3.5 (reference) prepared with conventional co-precipitation [0035] A reference Cu_0.1Mg_1.9AlO_3.5 catalyst was prepared with a conventional co-precipitation method. [0036] 3.67 g Cu(NO3)2^2.5H2O, 72.22 g Mg(NO3)2^6H2O and 56.38 g Al (NO₃)₃^9H₂O were dissolved in 295 g deionized water in a beaker. [0037] In a separate beaker, 87.49 g KOH and 13.49 g K₂CO₃ were dissolved in 329 g deionized water. [0038] The two solutions were pumped to a third beaker containing 200 g deionized water at 60^C with stirring. The pH value of the mixture was maintained at 10.0. After the co-precipitation process was complete, the mixture was stirred for an additional one hour. [0039] Subsequently, the slurry was filtered and washed with deionized water three times. The obtained paste was dried at 120°C for 12 hours and calcined at 600°C for 4 hours. Based on N2O pulse chemisorption result, the average Cu particle size was 8 nm on the synthesized catalyst. [0040] Example 2: Pre-treatment of Example 1 [0041] 1.00 g Cu_0.1Mg_1.9AlO_3.5 (Example 1) was loaded into a stainless steel autoclave with 29 g of a solution of 2:1 CH3OH to C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was heated to 170 °C at a 2 °C/min ramp rate and held at 170 °C for 18 hours, before cooling to room temperature. The alcohol mixture was decanted, and the catalyst was dried. Based on N₂O pulse chemisorption result, the average Cu particle size was 183 nm on the pre-treated catalyst. [0042] Example 3: 10 wt% Cu/Mg₂AlO_3.5 catalyst prepared with nano CuO [0043] 39.37 g Mg(NO3)2^6H2O and 29.09 g Al (NO3)3^9H2O were dissolved in 152 g deionized water in a beaker. [0044] In a separate beaker, 45.14 g KOH and 6.96 g K2CO3 were dissolved in 170 g deionized water. [0045] The two solutions were pumped to a third beaker containing 100 g deionized water at 60^C with stirring. The pH value of the mixture was maintained at 10.0. After the co-precipitation process was complete, the mixture was stirred for an additional one hour. Subsequently, the slurry was filtered and washed with deionized water three times. The paste was then dispersed in 50 g deionized water in a beaker. [0046] 1.43 g nano-sized CuO powders (purchased from Fisher Scientific) were added with stirring. The mixture was dried and calcined at 500°C for 4 hours. Based on N2O pulse chemisorption result, the average Cu particle size was 196 nm on the synthesized catalyst. [0047] Example 4: Cu0.14Mg1.86GaO3.5 (reference) prepared with conventional co- precipitation [0048] A reference Cu_0.14Mg_1.86GaO_3.5 catalyst was prepared with a conventional co-precipitation method. [0049] 1.82 g Cu(NO3)2^2.5H2O, 26.77 g Mg(NO3)2^6H2O and 15.24 g Al (NO₃)₃^9H₂O were dissolved in 111 g deionized water in a beaker. [0050] In a separate beaker, 40.76 g K₂CO₃ was dissolved in 146 g deionized water. [0051] The two solutions were pumped to a third beaker containing 200 g deionized water at 70^C with stirring. The pH value of the mixture was maintained at 7.0. After the co-precipitation process was complete, the mixture was stirred for an additional one hour. [0052] Subsequently, the slurry was filtered and washed with deionized water three times. The obtained paste was dried at 120°C for 12 hours and calcined at 600°C for 4 hours. Based on N2O pulse chemisorption result, the average Cu particle size was 4 nm on the synthesized catalyst. [0053] Example 5: Pre-treatment of Example 4 [0054] 1.00 g of Cu_0.14Mg_1.86GaO_3.5 (Example 4) was loaded into a stainless steel autoclave along with 29 g of a solution of 2:1 CH3OH to C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was heated to 170 °C at a 2 °C/min ramp rate and held at 170 °C for 18 hours before cooling to room temperature, decanting the alcohol mixture, and drying the catalyst. Based on N2O pulse chemisorption result, the average Cu particle size was 60 nm on the synthesized catalyst. [0055] Example 6: Cu_0.24Mg₂AlO_3.7 (reference) prepared with conventional co- precipitation [0056] A reference Cu0.24Mg2AlO3.7 catalyst was prepared with a conventional co-precipitation method. [0057] 7.33 g Cu(NO3)2^2.5H2O, 68.87 g Mg(NO3)2^6H2O and 50.89 g Al (NO3)3^9H2O were dissolved in 287 g deionized water in a beaker. [0058] In a separate beaker, 84.31 g KOH and 13.01 g K₂CO₃ were dissolved in 317 g deionized water. [0059] The two solutions were pumped to a third beaker containing 200 g deionized water at 60^C with stirring. The pH value of the mixture was maintained at 10.0. After the co-precipitation process was complete, the mixture was stirred for an additional one hour. [0060] Subsequently, the slurry was filtered and washed with deionized water three times. The obtained paste was dried at 120°C for 12 hours and calcined at 600°C for 4 hours. Based on N₂O pulse chemisorption result, the average Cu particle size was 9 nm on the synthesized catalyst. [0061] Example 7: Pre-treatment of Example 6 in alcohols [0062] 1.00 g Cu_0.24Mg₂AlO_3.7 (Example 6) was loaded into a stainless steel autoclave with 29 g of a solution of 2:1 CH3OH to C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was heated to 170 °C at a 2 °C/min ramp rate and held at 170 °C for 18 hours, before cooling to room temperature. The alcohol mixture was decanted, and the catalyst was dried. Based on N2O pulse chemisorption result, the average Cu particle size was 1415 nm on the pre-treated catalyst. [0063] Example 8: Pre-treatment of Example 6 in water [0064] 1.00 g Cu_0.24Mg₂AlO_3.7 (Example 6) was loaded into a stainless steel autoclave with 29 g water. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N₂ headspace. The autoclave was heated to 170 °C at a 2 °C/min ramp rate and held at 170 °C for 18 hours, before cooling to room temperature. The water was decanted, and the catalyst was dried. Based on N2O pulse chemisorption result, the average Cu particle size was 122 nm on the pre-treated catalyst. [0065] Example 9: CH3OH-C3H7OH reaction test on reference Cu0.1Mg1.9AlO3.5 catalyst (Example 1) [0066] 1.00 g of Example 1 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 29 g of a solution of 2:1 CH3OH-C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 1, 73% methanol conversion, 71% propanol conversion, 33% product isobutanol selectivity and 262 g/kg-h isobutanol productivity were achieved. [0067] Example 10: CH3OH-C3H7OH reaction test on pretreated Cu_0.1Mg_1.9AlO_3.5 catalyst (Example 2) [0068] 1.00 g of Example 2 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 29 g of a solution of 2:1 CH₃OH-C₃H₇OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N2, and vented after two hours to give a sealed system with an N₂ headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 1, 50% methanol conversion, 78% propanol conversion, 47% product isobutanol selectivity and 417 g/kg-h isobutanol productivity were achieved. As compared to reference catalyst Example 1, the pre-treatment improved isobutanol productivity by 59%, which is due to Cu particle size increase. [0069] Example 11: CH₃OH-C₃H₇OH reaction test on 10 wt% Cu/Mg₂AlO_3.5 catalyst (Example 3) [0070] 1.00 g of Example 3 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 29 g of a solution of 2:1 CH3OH-C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N2, and vented after two hours to give a sealed system with an N₂ headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 1, 42% methanol conversion, 74% propanol conversion, 52% product isobutanol selectivity and 459 g/kg-h isobutanol productivity were achieved. As compared to reference catalyst Example 1, this catalyst with large Cu particles improved isobutanol productivity by 75%. [0071] Example 12: CH₃OH-C₃H₇OH reaction test on reference Cu_0.14Mg_1.86GaO_3.5 catalyst (Example 4) [0072] 1.00 g of Example 4 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 29 g of a solution of 2:1 CH3OH-C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 1, 76% methanol conversion, 64% propanol conversion, 23% product isobutanol selectivity and 169 g/kg-h isobutanol productivity were achieved. [0073] Example 13: CH₃OH-C₃H₇OH reaction test on pre-treated Cu_0.14Mg_1.86GaO_3.5 catalyst (Example 5) [0074] 1.00 g of Example 5 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 29 g of a solution of 2:1 CH3OH-C3H7OH molar ratio. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 1, 74% methanol conversion, 71% propanol conversion, 32% product isobutanol selectivity and 254 g/kg-h isobutanol productivity were achieved. As compared to reference catalyst Example 1, the pre-treatment improved isobutanol productivity by 50%, which is due to Cu particle size increase. [0075] Example 14: CH₃OH-C₃H₇OH reaction test on Cu_0.24Mg₂AlO_3.7 reference catalyst (Example 6) [0076] The Cu0.24Mg2AlO3.7 catalyst from Example 6 (reference) was tested in a fixed-bed reactor under the conditions of 313^C, 600 psi, 11.4% propanol, 22.8% methanol, balance N₂, GHSV = 3,000 ml/g-h. 85% methanol conversion, 57% propanol conversion and 36% isobutanol selectivity were obtained. Isobutanol productivity was 213 g/kg-h under the testing conditions (Table 2). [0077] Example 15: CH₃OH-C₃H₇OH reaction test on pre-treated Cu_0.24Mg₂AlO_3.7 catalyst (Example 7) [0078] The pre-treated Cu0.24Mg2AlO3.7 catalyst from Example 7 was tested in a fixed-bed reactor under the conditions of 313^C, 600 psi, 11.4% propanol, 22.8% methanol, balance N₂, GHSV = 3,000 ml/g-h. 51% methanol conversion, 66% propanol conversion and 61% isobutanol selectivity were obtained. Isobutanol productivity was 474 g/kg-h under the testing conditions (Table 2). As compared to reference catalyst Example 6, the pre-treatment improved isobutanol productivity by 123%, which is due to Cu particle size increase. [0079] Example 16: CH3OH-C3H7OH reaction test on pre-treated Cu_0.24Mg₂AlO_3.7 catalyst (Example 8) [0080] The pre-treated Cu_0.24Mg₂AlO_3.7 catalyst from Example 8 was tested in a fixed-bed reactor under the conditions of 313^C, 600 psi, 11.4% propanol, 22.8% methanol, balance N2, GHSV = 3,000 ml/g-h. 26% methanol conversion, 56% propanol conversion and 67% isobutanol selectivity were obtained. Isobutanol productivity was 420 g/kg-h under the testing conditions (Table 2). As compared to reference catalyst Example 6, the pre-treatment improved isobutanol productivity by 97%, which is due to Cu particle size increase. [0081] Example 17: CH3OH-C2H5OH reaction test on reference Cu0.24Mg2AlO3.7 catalyst (Example 6) [0082] 1.00 g of Example 6 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 55.5 g of a solution of 6:1 CH₃OH-C₂H₅OH molar ratio. After testing at 325 °C for 15 hours, the liquid was analyzed by GC. As summarized in Table 3, 41% methanol conversion, 71% ethanol conversion, and 44% selectivity of product propanol, isobutanol and n-butanol were achieved. The total productivity of propanol, isobutanol and n-butanol was 308 g/kg-h. [0083] Example 18: CH₃OH-C₂H₅OH reaction test on pre-treated Cu_0.24Mg₂AlO_3.7 catalyst (Example 8) [0084] 1.00 g of Example 8 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 55.5 g of a solution of 6:1 CH3OH-C2H5OH molar ratio. After testing at 325 °C for 15 hours, the liquid was analyzed by GC. As summarized in Table 3, 21% methanol conversion, 68% ethanol conversion, and 52% selectivity of product propanol, isobutanol and n-butanol were achieved. The total productivity of propanol, isobutanol and n-butanol was 373 g/kg-h. As compared to reference catalyst Example 6, the pre-treatment improved propanol, isobutanol and n-butanol productivity by 21%, which is due to Cu particle size increase. [0085] Example 19: C₂H₅OH-C₂H₅OH reaction test on Cu_0.24Mg₂AlO_3.7 reference catalyst (Example 6) [0086] 1.00 g of Example 6 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 31 g of ethanol solution. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 4, 88% ethanol conversion,12.5% n-butanol selectivity and 183 g/kg-h n-butanol productivity were achieved. [0087] Example 20: C2H5OH-C2H5OH reaction test on pre-treated Cu0.24Mg2AlO3.7 catalyst (Example 7) [0088] 1.00 g of Example 7 was loaded into a catalyst basket and placed in a stainless steel autoclave along with 31 g of ethanol solution. The autoclave was sealed, charged with 2200 psi of ultra-high purity N₂, and vented after two hours to give a sealed system with an N2 headspace. The autoclave was then heated to 325 °C at a 2 °C/min ramp rate with stirring and held at 325 °C for 15 hours before cooling to room temperature. The liquid, catalyst basket, and autoclave weights were recorded. The liquid was analyzed by GC to provide information about methanol and propanol conversions and isobutanol productivity. As summarized in Table 4, 82% ethanol conversion, 17.1% n-butanol selectivity and 237 g/kg-h n-butanol productivity were achieved. As compared to reference catalyst Example 6, the pre-treatment improved isobutanol productivity by 30%, which is due to Cu particle size increase. [0089] Table 1 Example Catalyst composition Cu size Temp. Methanol Propanol Isobutanol Isobutanol (nm) (°C) conversion conversion selectivity productivity

[0090] Table 2 Example Catalyst composition Cu size Temp. Methanol Propanol Isobutanol Isobutanol (nm) (°C) conversion conversion selectivity productivity

[0091] Table 3 Example Catalyst Cu size Temp. Methanol Ethanol Propanol and Propanol and composition (nm) (°C) conversion conversion butanol butanol productivity

[0092] Table 4 Example Catalyst composition Cu size Temp. Ethanol n-butanol n-butanol (nm) (°C) conversion selectivity productivity

[0093] While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.

Claims

What is claimed is: 1. An alcohol condensation catalyst for the synthesis of isobutanol comprising: a Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst; wherein M²⁺ comprises divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof; wherein M³⁺ comprises trivalent aluminum, gallium, chromium, or combinations thereof; and wherein the Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺oxide catalyst has an average Cu or CuO particle size greater than or equal to 20 nm.

2. The catalyst of claim 1 wherein the average Cu or CuO particle size is in the range of 50 nm to 500 nm.

3. The catalyst of any one of claims 1-2 wherein the Cu or CuO is present in an amount of 0.5 wt% to 50 wt%.

4. The catalyst of any one of claims 1-3 wherein the M²⁺ is present as M²⁺O in an amount of 1 wt% to 98 wt%.

5. The catalyst of any one of claims 1-4 wherein the M³⁺ is present as M³⁺2O3 in an amount of 1 wt% to 98 wt%.

6. The catalyst of any one of claims 1-5 wherein the M²⁺ is divalent magnesium, and wherein the M³⁺ is trivalent aluminum.

7. The catalyst of any one of claims 1-6 wherein the M²⁺ is divalent magnesium, and wherein the M³⁺ is trivalent gallium.

8. The catalyst of claim 1 wherein: the average Cu or CuO particle size is in a range of 50 nm to 500 nm; the Cu or CuO is present in an amount of 1 wt% to 30 wt%; the M²⁺ is present as M²⁺O in an amount of 5 wt% to 75 wt%; and M³⁺ is present as M³⁺ ₂O₃ in an amount of 5 wt% to 75 wt%.

9. The catalyst of claim 8 wherein the M²⁺ is divalent magnesium, and wherein the M³⁺ is trivalent aluminum or trivalent gallium.

10. A method of making an alcohol condensation catalyst for the synthesis of isobutanol comprising: preparing a Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst; wherein M²⁺ is divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof; and wherein M³⁺ is trivalent aluminum, gallium, chromium, or combinations thereof; and contacting the Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺oxide catalyst with a solvent at a temperature for a time sufficient to form a pre-treated catalyst having an average Cu particle size greater than or equal to 20 nm.

11. The method of claim 10 wherein the temperature is in a range of 100°C to 300°C.

12. The method of any one of claims 10-11 wherein the time is in a range of 1 to 50 hr.

13. The method of any one of claims 10-12 wherein the solvent comprises water, an organic solvent, an alcohol, an aldehyde, a ketone, an ether, an ester, a polyol, a hydrocarbon, or combinations thereof.

14. The method of any one of claims 10-13 wherein the solvent comprises an alcohol and wherein the alcohol comprises methanol, ethanol, a propanol, a butanol, a pentanol, a hexanol, or combinations thereof.

15. The method of any one of claims 10-14 further comprising: drying the pre-treated catalyst.

16. The method of any one of claims 10-15 wherein the Cu or CuO is present in an amount of 0.5 wt% to 50 wt%.

17. The method of any one of claims 10-16 wherein M²⁺ is present as M²⁺O in an amount of 1 wt% to 98 wt%.

18. The method of any one of claims 10-17 wherein M³⁺ is present as M³⁺ ₂O₃ in an amount of 1 wt% to 98 wt%.

19. The method of any one of claims 10-18 wherein the M²⁺ is divalent magnesium, and wherein the M³⁺ is trivalent aluminum or trivalent gallium.

20. The method of any one of claims 10-19 wherein the Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst is prepared using co-precipitation, deposition-precipitation, impregnation, or sol-gel.

21. A method of producing isobutanol or n-butanol comprising: reacting ethanol or propanol with methanol in the presence of an alcohol condensation catalyst under reaction conditions to produce isobutanol or reacting ethanol with ethanol in the presence of an alcohol condensation catalyst under reaction conditions to produce n-butanol; wherein the alcohol condensation catalyst comprises a Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺oxide catalyst; wherein M²⁺ comprises divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof; wherein M³⁺ comprises trivalent aluminum, gallium, chromium, or combinations thereof; and wherein the Cu/M²⁺M³⁺ oxide or CuO/M²⁺M³⁺oxide catalyst has an average Cu particle size greater than or equal to 20 nm.

22. The method of claim 21 wherein the reaction conditions comprise one or more of: a temperature in a range of 100°C to 500°C; or a pressure in a range of 5 kPa to 30,000 kPa.

23. A method of making an alcohol condensation catalyst for the synthesis of isobutanol comprising: providing Cu or CuO particles having an average Cu or CuO particle size greater than or equal to 20 nm; and depositing M²⁺M³⁺oxide on the Cu or CuO particles to form a Cu/M²⁺M³⁺oxide or CuO/M²⁺M³⁺oxide catalyst; wherein M²⁺ comprises divalent magnesium, calcium, strontium, barium, zinc, or combinations thereof; and wherein M³⁺ comprises trivalent aluminum, gallium, chromium, or combinations thereof.

24. The method of claim 23 wherein the Cu or CuO is present in an amount of 0.5 wt% to 50 wt%.

25. The method of any one of claims 23-24 wherein M²⁺ is present as M²⁺O in an amount of 1 wt% to 98 wt%.

26. The method of any one of claims 23-25 wherein M³⁺ is present as M³⁺2O3 in an amount of 1 wt% to 98 wt%.

27. The method of any one of claims 23-26 wherein the M²⁺ is divalent magnesium, and wherein the M³⁺ is trivalent aluminum or trivalent gallium.

28. The method of any one of claims 23-27 wherein the M²⁺M³⁺oxide is deposited using co-precipitation, deposition-precipitation, impregnation, or sol-gel.