A kind of methane aromatization catalyst and its production and application
Technical field
The present invention relates to a kind of catalyzer, specifically, relate to a kind of catalyzer that is used in direct synthesis of arene with methane.
The invention still further relates to above-mentioned Preparation of catalysts method.
The invention still further relates to the application of this catalyzer in methane system aromatic hydrocarbons.
Background technology
Methane can thermal transition generate benzene under greater than 900 ℃ condition, can obtain 6~10% benzene under 1200~1300 ℃ condition.
For the Methane Conversion under the catalytic condition, Science in 1966 have reported the result of methyl hydride catalyzed synthetic aromatic hydrocarbons on silica-gel catalyst, at 1000 ℃ of aromatics yields that obtain 4.2-7.2%.In addition, reported methane the eighties in 20th century in succession at the multi-functional complex metal oxides of boron nitride (BN), supersiliceous zeolite supports the result of the synthetic aromatic hydrocarbons of catalysis on Pt-Cr and Ga catalyzer and the carbon fibre material.
1993, Xie Maosong etc. at first reported the aromatization that methane is fastened at Mo/HZSM-5 and Zn/HZSM-5 catalyst body in Chinese patent (CN1102359A).
Zhang Hongbin etc. have reported that methane is at WO in Chinese patent (CN1170633)
3Generate the process of aromatic hydrocarbons on the/ZSM-5 catalyzer.
Xu Yide etc. report in Chinese patent (CN1266041) through the methane aromatizing process on the Mo/ZSM-5 catalyzer of microwave treatment, find that arenes selectivity is good through methane conversion height on the catalyzer of microwave treatment, and can realize low carbon deposit.
Lv Yuan etc. report the methane aromatizing process on the Mo/ZSM-5 catalyzer of handling through high-temperature vapor in Chinese patent (CN1254618), find to reduce through methane coke content on the catalyzer of steam treatment, and stability improves.
Shu Yuying etc. have reported that in Chinese patent (CN1271622) methane makes the process of aromatic hydrocarbons on the MCM-22 zeolite catalyst that Mo supports.
Xu Yide etc. have reported that in Chinese patent (CN1167653) methane is adding the second component R (R=La, Ce, Pr, the aromatization process on Mo-R/HZSM-5 catalyzer Nd).
Liu Hongmei etc. report that in " catalysis journal " interpolation of Co has improved the stability of Mo/HZSM-5 catalyzer in reaction process.
Dong Qun etc. report the influence of the interpolation of Fe, Cr, Co, Ga to Mo/HZSM-5 catalyst methane aromatization in " Journal of Molecular Catalysis ", find that change has taken place the performance of catalyzer.
Wang Qiying etc. have reported the Effect on Performance of rare-earth additive Y to Mo/HZSM-5 catalyst methane aromatization in " Guangzhou chemical industry ", find that methane conversion improves.
Shu Yuying etc. have reported the interpolation of Ru to Mo/HZSM-5 catalyst methane anaerobic dehydrogenation aromatization Effect on Performance in " catalysis journal ", find that the interpolation of Ru has improved activity of such catalysts.
Tan Ping even waits and has reported that in " oil and gas chemical industry " precious metal and Li, P etc. to the influence of Mo/HZSM-5 catalyzer, find that metal Pt adds component and reduces carbon distribution to a certain extent, but the reactive behavior of catalyzer decrease.
Xiong Zhitao etc. have reported the influence of the interpolation of Mg to the W/HZSM-5 catalyst performance in " Catalysis Letters ".
Summary of the invention
The object of the present invention is to provide a kind of catalyzer of methane aromatizing, improve the stability that methane directly prepares the aromatic hydrocarbons process.
The invention provides a kind of catalyzer of direct synthesis of arene with methane, this catalyzer consists of A-R/D, that is: active constituent-auxiliary agent/carrier.Wherein, at least a in the oxide compound of active constituent A Wei Rhenium and/or molybdenum, its weight loading is 0.01-15%; Auxiliary agent R is an alkali earth metal, and its weight loading is 0.01-10%; Carrier D can comprise ZSM-5, ZSM-11, MCM-22, MCM-49 or MCM-56 etc. for being used for the molecular sieve of direct synthesis of arene with methane.
Be MoO with the active ingredient among the present invention
3Be the best, its content is 2~12% better.
The alkali earth metal that is used as auxiliary agent among the present invention is best with Mg, and its weight loading is better with 0.03~1.5%.
Preparation of catalysts method provided by the present invention is:
A) with molecular sieve with nitric acid ammonia solution (0.8 mol) 80-100 ℃ down exchange for several times, washing, 400-800 ℃ roasting 1-5 hour;
B) molecular sieve powder that obtains with the solution impregnation step a that alkali earth metal is provided, dipping time 1-24 hour, drying, 400-800 ℃ roasting 1-8 hour;
C) powder that obtains with the solution impregnation step b that Re and/or Mo element be provided, dipping time 1-24 hour, drying, 400-800 ℃ roasting 2-8 hour;
D) product that makes of step c is ground into the 16-32 order.
Above-mentioned steps b and step c can repeat arbitrarily, and the order of step b and step c can be changed.
In the presence of catalyzer of the present invention, the condition of the directly synthetic aromatic hydrocarbons of low-carbon alkanes such as methane is: be reflected in the fixed bed reactor system of continuously feeding and carry out, reaction raw materials can be pure methane or methane, carbon dioxide mix gas, reaction pressure is 0.05~2.5MPa, temperature of reaction is 650~800 ℃, and the charging air speed is 100~5000ml/g.h.
In methane aromatization, use catalyzer provided by the invention, can improve stability than the catalyzer that does not add alkali earth metal.
Description of drawings
Fig. 1 represents methane conversion and the selectivity of product on the 6Mo/ZSM-5 catalyzer.
Fig. 2 represents the comparison of methane conversion on the different 6MoxMg/ZSM-5 catalyzer.
Embodiment
With following example method of the present invention is described, and the present invention is not subjected to the restriction of these methods, such as: only enumerate Na type ZSM-5 molecular sieve among the embodiment, and to those skilled in the art, be readily appreciated that for embodiment equally suitable to ZSM-5, ZSM-11, MCM-22, MCM-49, MCM-56 equimolecular sieve.In like manner, in the Preparation of catalysts method, maturing temperature 400-800 ℃ can, be not limited to 500 ℃ among the embodiment, and roasting time is not limited to embodiment too.
Embodiment 1
Na type ZSM-5 molecular sieve is exchanged 3 times under 80~100 ℃ condition with the nitric acid ammonia solution, wash 3 times, roasting 3 hours in 550 ℃ of air atmospheres then, it is standby to obtain H-ZSM-5.Taking by weighing 10 gram H-ZSM-5, to place concentration be the Mg (NO of 0.039g/ml
3)
2In 20 milliliters of the solution, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, it is 20 milliliters of the ammonium molybdate solutions of 0.028g/ml that the gained calcining matter places concentration, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, products therefrom (catalyst A) compression molding, it is stand-by to be ground into 16~32 orders.
Embodiment 2
Na type ZSM5 molecular sieve is exchanged 3 times under 80~100 ℃ condition with the nitric acid ammonia solution, wash 3 times, roasting 3 hours in 550 ℃ of air atmospheres then, it is standby to obtain H-ZSM-5.Taking by weighing 10 gram H-ZSM-5, to place concentration be the Mg (NO of 0.053g/ml
3)
2In 20 milliliters of the solution, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, it is 20 milliliters of the ammonium molybdate solutions of 0.028g/ml that the gained calcining matter places concentration, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, products therefrom (catalyst B) compression molding, it is stand-by to be ground into 16~32 orders.
Embodiment 3
Na type ZSM-5 molecular sieve is exchanged 3 times under 80~100 ℃ condition with the nitric acid ammonia solution, wash 3 times, roasting 3 hours in 550 ℃ of air atmospheres then, it is standby to obtain H-ZSM-5.Taking by weighing 10 gram H-ZSM-5, to place concentration be the Mg (NO of 0.053g/ml
3)
2In 20 milliliters of the solution, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 3 hours in 550 ℃ of air atmospheres then, it is 20 milliliters of the ammonium molybdate solutions of 0.037g/ml that the gained calcining matter places concentration, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, products therefrom (catalyzer C) compression molding, it is stand-by to be ground into 16~32 orders.
Comparative example
Na type ZSM-5 molecular sieve is exchanged 3 times under 80~100 ℃ condition with the nitric acid ammonia solution, wash 3 times, roasting 3 hours in 550 ℃ of air atmospheres then, it is standby to obtain H-ZSM-5.Taking by weighing 10 gram H-ZSM-5, to place concentration be 20 milliliters of the ammonium molybdate solutions of 0.028g/ml, standing over night, evaporate to dryness in 70~80 ℃ of water-baths, oven dry is 4 hours in 120 ℃ of air atmospheres, roasting 6 hours in 500 ℃ of air atmospheres then, products therefrom (catalyzer d) compression molding, it is stand-by to be ground into 16~32 orders.
Embodiment 4
Methane aromatizing system benzene is reflected on the continuous flow fixed bed and carries out, and reactor is the crystal reaction tube of internal diameter 7~8mm, and the each loading amount of catalyzer is 0.4 gram.Reaction pressure is 0.1MPa, and temperature of reaction is 720 ℃, and the methane feed air speed is 1500ml/g.h.Switching to unstripped gas after 30 minutes with the He gas disposal (consists of 9.54%Ar, 1.91%CO down at 720 ℃
2, 88.55%CH
4) carry out catalyzed reaction, adopting Ar is that interior mark calculates carbon distribution in interior carbon number balance result.Its result is referring to Fig. 1 and Fig. 2.