WO2009016649A1

WO2009016649A1 - A process for the preparation of a mixture of carbonaceous products from proteinaceous materials

Info

Publication number: WO2009016649A1
Application number: PCT/IN2008/000130
Authority: WO
Inventors: Palanisamy Thanikaivelan; Arakkonam Mohan Thiruvilan; Bangaru Chandrasekaran; Jonnalagadda Raghava Rao; Balachandran Unni Nair
Original assignee: Council of Scientific and Industrial Research CSIR
Current assignee: Council of Scientific and Industrial Research CSIR
Priority date: 2007-08-01
Filing date: 2008-03-07
Publication date: 2009-02-05
Anticipated expiration: 2010-02-01

Abstract

Proteinaceous materials such as the byproducts obtained from the leather industry are pyrolyzed under controlled conditions of temperature and atmosphere and subsequently cooled to obtain a mixture of carbonaceous products. The products find enormous application in wide ranging industrial areas. An organic liquid, which is optionally obtained as byproduct, also finds significant industrial application.

Description

"A PROCESS FOR THE PREPARATION OF A MIXTURE OF CARBONACEOUS PRODUCTS FROM PROTEINACEOUS MATERIALS"

Field of the Invention The present invention relates to a process for the preparation of a mixture of carbonaceous products from proteinaceous materials. More particularly, the present invention provides an improved process for obtaining value added products from proteinaceous materials whereby the protein is converted into carbonaceous products, having high value industrial application. The process provides an eco-friendly solution for effective utilization of the proteinaceous solid wastes generated by different industries. Thus, it is envisaged to find enormous potential application in slaughter house, meat packing, leather and related industries in providing a green solution for utilizing the skin, hide and leather co-products. The carbonaceous product of the invention finds numerous industrial applications as ingredient for making rubber tires, reinforcement in composites, dry lubricant. They are also envisaged to have enormous application in the areas relating to nanotechnology, electronics, optics, material sciences and allied fields. Moreover, the organic liquid produced optionally as a byproduct of the process provides a rich source of amino acid-peptide mixture, which may find application in biotechnological industries.

Background of the Invention and Description of Prior Art

Numerous amounts of solid wastes are generated by protein processing industries. Leather industry figures prominently among this class of industries. Solid co-products from the tanning industry are unavoidable. This is because leather processing is primarily associated with purification of a multi-component, skin, to obtain a single protein, collagen. The intrinsic nature of the leather processing steps and the nature of chemicals employed are also responsible for the generation of certain quantum of solid co-products. The formation of solid co- products starts at the very first operation namely, desalting and trimming the raw material, and prolongs through almost all unit processes and operations till the end of the process sequence, namely buffing operation. Tanned co-products include chrome shavings, wet blue trimmings, wet blue split wastes, vegetable tanned leather shavings; combination tanned leather shavings, buffing dust, crust trimmings, finished leather trimmings, leather scraps from leather product industries such as footwear, garments, goods, upholsteries. The tanned co-products, in general, consist of chromium and protein. Since chromium is known for its toxicity, the disposal of chromium containing protein co-products generated from the tanning industries has been identified as a serious, problem from the viewpoint of environmental safety. Further, the leather from the used and discarded product after its life cycle forms a major and environmentally challenging waste.

Historically, the tanned cchproducts were disposed of in landfills. However, due to the local pollution control agency restrictions as well as the presence of valuable protein source, the tanning industry seeks alternatives to dumping as reported by Lipsett (Journal of American Leather Chemists Association, 77, 291 , 1982). These co-products can be utilized with or without the presence of chromium. The direct application of tanned co-products is many fold such as the manufacture of bonded leather, leather boards, fibrous sheets grafted with acrylates, insulators and building materials after reacting with polyisocyanates, composites for footwear, sound-proof roofing material, preparation of basic chromium sulphate salt etc. as described by Rao et al (Journal of American Leather Chemists Association, 99, 170, 2004).

The indirect utilization of ^tanned co-products is generally based on separating the protein-bound chromium and using the protein and chromium fractions for several applications. The combination of alkali and enzymes is able to recover the chromium from the protein fractions and is widely employed in many parts of the world, as reported by Taylor et al (Journal of American Leather Chemists Association, 85, 264, 1990). Many researchers have recovered chromium by wet air oxidation and peroxide treatment, detanned chrome leather wastes for gelatin preparation and isolation of collagen fibres, acid hydrolyzed the tanned co- products in to chromium containing protein hydrolysate usable in the retanning of wet blue leathers as reviewed by Rao et al (Journal of American Leather Chemists Association, 99, 170, 2004). All the above studies show that the separation and recovery of protein bound chromium involve tedious ^"process steps and need huge investment as stated by Heidemann (Journal of American Leather Chemists Association, 86, 331, 1991). In such cases, the contamination of the one with the other is unavoidable.

The major limitation of all these processes is that the issue of addressing the possibility of using the proteinous substance, free from or laden with chromium, has remained unresolved. This has prompted various researchers to explore possibilities for providing option of decomposing the proteinous substance for producing substances, which are likely to have industrial applications.

A series of patents have been filed by Breu (US Patent 5,453,164); Lewis (US Patent 4,122,036); Camacho (US Patent 5,544,597) for pyrolyzing the wastes like plastic waste, tires, materials from automobile shredding operations, municipal wastes, containers and trays of plastic material, rubber, leather, garbage, sewage sludge, coal, oil shale, broken asphalt. However, all these methods convert solid hydrocarbons into gases, liquid hydrocarbons, and char, thus primarily aiming at the generation of burnable fuel.

Pyrolysis is a process by which organic materials are heated to high temperatures in the absence of significant amounts of oxygen, i.e., in an inert atmosphere, whereby the organic material is thermally decomposed into simpler components. The products of pyrolysis are gases and solids having various constituents which determine their volatility and density. The term "gas" includes non-condensable gases and also condensable vapors. These products are released at high temperature, which must be reduced in order to condense the gases into their liquid constituents. Pyrolysis differs from incineration or combustion in that, in the latter two processes, the organic material is significantly oxidized whereas in the former no significant oxidation takes place. Pyrolysis of the organic wastes generally results in the formation of three classes of products: (a) a gas comprising hydrogen and/or methane;

(b) a liquid mixture comprising water, tar, oil and/or other organics;

(c) a solid residue comprising carbon matrix

The leather co-products that are derived from the waste streams are organic in nature. A method of treating liquid and solid tannery waste material containing chromium and organic matter to recover trivalent chromium and to produce fuel products has been developed by Muralidhara (US Patent 4,332,584). The method comprises primarily five steps namely pyrolizing the wastes at 260 to '500⁰C, separating the burnable fuel products from chromium containing residue, burning the fuel products followed by recovering chromium compounds from the residue by dissolution in about 1M sulfuric acid solution and recycling the recovered chromium to tanning. The process involves the use of chromium containing protein wastes as one of the raw material, presence of oxygen above 10% and low temperature. Further, the process requires a cyclone separator for separating the carbonaceous material from chromium containing residue. This obviously adds to cost and tends to render the process uneconomical.

Jones (US Patent 4,086,319) disclosed a process which involves the incineration in an oxidizing atmosphere of tannery wastes at elevated temperatures between 426 and 649⁰C₁ to convert the organic material to gases and the chromium material to ash. The process is directed only at the recovery of chromium, in trivalent or hexavalent form, from the ash by conventional leaching operations. Further, the process involves oxygen atmosphere.

The major focus of all these processes relating to pyrolysis of industrial wastes, available in the prior art, has been either to prepare fuel or to separate chromium, either in trivalent or hexavalent form. Therefore, the inventors realized that there exists a need for the development of a process which results in the production of commercially useful carbonaceous products from proteinous wastes. Objects of the Invention

The main objective of the present invention is to provide a process for the preparation of a mixture of carbonaceous products from proteinaceous materials, which precludes the limitations as stated above. Another objective of the present invention is to provide a process wherein two or more valuable compounds can be obtained.

Yet another objective of the present invention is to provide a process wherein the duration of the process can be as low as 20 minutes.

Still another objective of the present invention is to provide a process that avoids the formation of carcinogenic chromium(VI).

Another objective of the present invention is to provide a process that leads to the production of significant amount of chromium(lll) based carbon matrices.

Still another objective of the present invention is to provide a process that is economical and free from the use of costly accessories like cyclone separator.

Summary of the Invention

Accordingly, the present invention provides a process for the preparation of a mixture of carbonaceous products from proteinaceous materials, wherein the process steps comprise: a) heating the proteinaceous materials at a temperature in the range of

200 - 1500 degree C at the rate of 10 - 40 degree C per minute under inert atmosphere for a period in the range of 20 - 720 minutes to obtain solid carbonaceous products and vapours; b) allowing the vapours as formed in step (a) to escape or optionally get condensed at a temperature in the range of 4 - 24 degree C to get organic liquid product; c) cooling the solid carbonaceous products as formed in step (a) at a temperature in the range of 4 - 24 degree C for a period in the range of 10 - 120 minutes to get a mixture of carbonaceous products. In an embodiment of the present invention, the proteinaceous materials used may be selected from raw hide trimmings, limed split scraps, hide powder, wet blue trimmings, wet blue split wastes, chrome tanned leather shavings, vegetable tanned leather shavings, combination tanned leather shavings, buffing dust, crust trimmings, finished leather trimmings, leather scraps from leather product industries, either individually or in combination.

In another embodiment of the present invention, the inert gas used may be selected from nitrogen, argon, helium.

Description of the Invention

The proteinaceous materials are taken in a reactor fitted with provision for inert gas channel at the lid and a channel for collection of vapors at the top. Reactor is closed on the top after inserting the inert gas channel. Then the vapor collection channel of the reactor is connected to the condenser and liquid collection container, which are made airtight. The top end of the condenser is connected to a water trap in order to avoid the passage of oxygen into the reactor. Proteinaceous materials are heated at a temperature in the range of 200 - 1500⁰C at the heating rate of 10 - 4O⁰C per minute under inert atmosphere for a period in the range of 20 - 720 minutes. The vapors formed are either allowed to escape or optionally condensed at a temperature in the range of 4 - 24⁰C to get organic liquid product in an air tight container. The reactor is cooled at a temperature in the range of 4 - 24⁰C for a period of 10 - 120 minutes to get a mixture of carbonaceous products.

The inventive step of the present invention lies in pyrolyzing proteinaceous materials under controlled temperature and atmosphere to produce a mixture of carbonaceous products which find enormous potential industrial applications.

The invention is described in detail in the following examples, which are provided by way of illustration only and therefore should not be construed to limit the scope of the present invention. Example 1

10 gms dry chrome shavings were added to the borosil glass reactor. The inlet of a nitrogen cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 200⁰C at a rate of 1O⁰C per minute for 20 minutes in nitrogen atmosphere. Organic liquid was collected in a container by cooling the vapors at 24⁰C using water circulation. Liquid was tested for the presence of Cr(VI) using diphenyl carbazide and found to be negative. The UV-visible spectra showed a peak at 265 nm. Ninihydrin test showed .pink color formation indicating the presence of peptides or aminoacids. The reactor was cooled for 45 minutes at 24⁰C. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis revealed the micro scale structures in the derived carbon product. Energy dispersive x-ray analysis showed the presence of chromium in the resulted carbon product. Applications of this carbon product include ingredient for making rubber tires, reinforcement in composites, dry lubricant etc.

Example 2 A mixture of 5 gms buffing dust, 5 gms combination tanned leather shavings and 10 gms -vegetable tanned leather shavings were added to the stainless steel reactor. The inlet of argon cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 500⁰C at a rate of 20⁰C per minute for 25 minutes in argon atmosphere. Heating was continued for another 695 minutes. Organic liquid was collected in a container by cooling the vapors at 4⁰C using ice water bath. The UV-visible spectra showed a peak at 265 nm. Ninihydrin test showed pink color formation indicating the presence of peptides or aminoacids. The reactor was cooled for 10 minutes at 4⁰C. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis reveals the micro scale structures in the derived carbon product. Applications of this carbon product include ingredient for making rubber tires, reinforcement in composites, dry lubricant etc. Example 3

10 gms raw hide trimmings were added to the stainless steel reactor. The inlet of argon cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 75O⁰C at a rate of 25⁰C per minute for 30 minutes in argon atmosphere. Heating was continued for another 45 minutes. Organic liquid was collected in a container by cooling the vapors at 4⁰C using ice water bath. The UV-visible spectra showed a peak at 265 nm. Ninihydrin test showed pink color formation indicating the presence of peptides or aminoacids. The reactor was cooled for 20 minutes at 16⁰C using cool air circulation. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis reveals the micro and nano scale structures in the derived carbon product. Presence of spherical structures was evident. The diameter of the carbon spherical structures was 200-500 nm. Applications of this carbon product include ingredient for making rubber tires, reinforcement in composites, dry lubricant etc.

Example 4

10 gms dry chrome shavings were added to the stainless steel reactor. The inlet of argon cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 80O⁰C at a rate of 4O⁰C per minute for 20 minutes in argon atmosphere. Heating was continued for another

20 minutes. Organic liquid was collected in a container by cooling the vapors at 24⁰C using water circulation. Liquid was tested for the presence of Cr(VI) using diphenyl carbazide and found to be negative. The UV-visible spectra showed a peak at 265 nm. Ninihydrin test showed pink color formation indicating the presence of peptides or aminoacids. The reactor was cooled for 120 minutes at 24⁰C. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis reveals the micro and nano scale structures in the derived carbon product. Presence of tubular structures with .branches was evident. The diameter of the carbon tubular structures was 100- 200 nm. Εnergy dispersive x-ray analysis shows the presence of chromium in the resulted carbon product. Applications of this carbon product include ingredient for making rubber tires, reinforcement in composites, dry lubricant, nanotechnology, (electronics, optics, material sciences and other fields.

Example 5

A mixture of 5 gms wet blue trimmings, 5 gms wet blue split wastes, 2 gms hide powder and 2 gms limed split scraps were added to the quartz reactor. The inlet of a helium cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 1200⁰C at a rate of 4O⁰C per minute for 30 minutes in helium atmosphere. Heating was continued for another 180 minutes. Organic liquid was collected in a container by cooling the vapors at 24⁰C using water circulation. Liquid was tested for the presence of Cr(VI) using diphenyl carbazide and found to be negative. The UV-visible spectra showed a peak at 265 nm. Ninihydrin test showed pink color formation indicating the presence of peptides or aminoacids. The reactor was cooled for 40 minutes at 16⁰C. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis reveals the micro and nano scale structures in the derived carbon product. Presence of tubular structures was evident. Energy dispersive x-ray analysis shows the presence of chromium in the resulted carbon product. Applications of this carbon product include nanotechnology, electronics, optics, material sciences and other fields. Example 6

A mixture of 5 gms crust trimmings, 5 gms finished leather trimmings and 2 gms leather scraps were added to the quartz reactor. The inlet of a helium cylinder was fitted to the lid of the reactor and closed tightly. The vapor collection channel of the reactor was tightly connected to the condenser. The bottom neck of the condenser was tightly connected to a container. The top neck of the condenser was tightly connected to a water trap for avoiding oxygen passage into the reactor. The reactor was heated to 1500⁰C at a rate of 4O⁰C per minute for 40 minutes in helium atmosphere. Organic liquid was collected in a container by cooling the vapors -at 24⁰C using water circulation. Liquid was tested for the presence of Cr(VI) using diphenyl carbazide and found to be negative. The reactor was cooled for 40 minutes at 16⁰C. Then the carbon product was collected and stored in a container. Scanning electron microscopic analysis reveals the micro and nano scale structures in the derived carbon product. Presence of tubular structures was evident. Applications of this carbon product include nanotechnology, electronics, optics, material sciences and other fields.

Advantages of the Invention:

The following are the advantages of the present invention: 1. This process hardly requires any complicated control measures.

2. This process does not require additional accessories such as cyclone separator.

3. There is no additional step of separating chromium from carbon product.

4. The process does not convert chromium(lll) to chromium(VI). 5. The product of the invention finds numerous industrial applications such as ingredient for making rubber tires, reinforcement in composites, dry lubricant, nanotechnology, electronics, optics, material sciences and other fields

6. The organic liquid produced optionally as a byproduct of the process provides a rich source of amino acid-peptide mixture, which has potential applications in biotechnological industries.

Claims

We claim:

1. A process for the preparation of a mixture of carbonaceous products from proteinaceous materials, wherein the process steps comprise: a) heating the proteinaceous materials at a temperature in the range of 200 - 1500 degree C at the rate of 10 - 40 degree C per minute under inert atmosphere for a period in the range of 20 - 720 minutes to obtain solid carbonaceous products and vapours; b) allowing the vapours as formed in step (a) to escape or optionally get condensed at a temperature in the range of 4 - 24 degree C to get organic liquid product; c) cooling the solid carbonaceous products as formed in step (a) at a temperature in the range of 4 - 24 degree C for a period in the range of 10 - 120 minutes to get a mixture of carbonaceous products.

2. A process according to claim 1 , wherein the proteinaceous materials used are selected from raw hide trimmings, limed split scraps, hide powder, wet blue trimmings, wet blue split wastes, chrome tanned leather shavings, vegetable tanned leather shavings, combination tanned leather shavings, buffing dust, crust trimmings, finished leather trimmings, leather scraps from leather product industries, either individually or in any combination.

3. A process according to any preceding claims, wherein the inert gas used is selected from nitrogen, argon, helium.