Title of Invention

AN IMPROVED PROCESS FOR THE REGENERATION OF SPENT COPPER OXIDE HYDROGENATION CATALYSTS AT LOWER TEMPERATURE

Abstract

Spent chrome free copper oxide and copper chromite catalysts in pellet form which have been used for hydrogenating nitroaromatic compounds to their corresponding amino derivatives are regenerated to their active states by a novel process which involves treating mem first with a mixture of water vapor and nitrogen at 60° to 250°C and thereafter oxidative gasification of me residual materials at 75° to 300 °C.

Full Text

FORM 2 THE PATENT ACT, 1970 (39 of 1970) AND THE PATENT RULES, 2003 COMPLETE SPECIFICATION (See Section 10, Rule 13) 1. TITLE OF THE INVENTION: AN IMPROVED PROCESS FOR THE -REGENERATION OF SPENT COPPER OXIDE HYDROGENATION CATALYSTS AT LOWER TEMPERATURE. 2. APPLICANT(S) (a) Name: M/s. HINDUSTAN ORGANIC CHEMICALS LIMITED (b) Nationality: Indian (c) Address: Mr. A. S. Didolkar, CMD 81, Maharshi Karve Road, MUMBAI - 400 002, Maharashtra, India. 3. PREAMBLE TO THE DESCRIPTION : COMPLETE SPECIFICATION The following specification particularly describes the invention and the manner in which it is to be performed: PRIOR ART It is reported that some alumina catalysts used for Clause reaction could be regenerated by washing them first with liquid water to remove soluble organic materials from the surfaces of the catalysts and thereafter by controlled oxidative gasification of the residual materials with air and nitrogen mixture at elevated temperatures of 450° to 480 °C (Z. M George, R G. Carvell and A. Datta, Frontiers in Chemical Reaction Engineering, Vol. n, P. 171, 1984, edited by L. K. Doraiswamy and R. A. Mashelkar, National Chemical Laboratory, Pune, India). Similarly, water along with air was also used to regenerate the spent catalyst at about 400 °C in a fluidized bed process for oil cracking (George D Mayers et. al, US Patent No. 44179575, 1983). In another process, a catalyst consisting of a mixture of oxides of Al, Mg, Mn, Cr, Zn and Cu or Fe has been regenerated by treating it with a mixture containing water vapor, air and nitrogen at 350° to 500 °C (Patent No. SU 264358, 1970). Regeneration with air and nitrogen mixtures of some spent catalysts containing Cu and Cr oxides at about 300°C has been claimed in an aniline manufacturing process (Indian Patent No. 158506, 1984 to Hindustan Organic Chemicals Limited). The novelty of the present invention is that the regeneration of the catalysts can be done at about 60° to 250° C which is quite low and eliminates the possibility of sintering of the catalysts which diminishes their activity. OBJECTIVE OF THE PRESENT INVENTION The objective of the present invention is to remove the chemisorbed materials as well as coke on the surfaces of spent chrome free copper oxide and copper chromite catalysts industrially used for the hydrogenation of nitrobenzene to aniline to restore their original activity. SUMMARY OF THE INVENTION This invention relates to a process for the complete gasification of the carbonaceous materials from the surfaces of the catalysts pellets packed in a fixed bed. The catalysts which can be regenerated in-situ by the method of the present invention are pelletized form of chrome-free copper oxide containing La and Ce as promoters with compounds of Ca, Al and Si as supports as well as commercial copper chromite catalysts which have been used to hydrogenate nitroaromatic compounds to their amine derivatives in fixed bed reactors. After prolonged use in the hydrogenation process, the catalysts get deactivated due to the chemisorption of reactant materials, the product and amine by-products as well as coke on their surfaces. The said chemisorbed deposits can be removed only partially by controlled gasification with a mixture of air and an inert gas to restore some catalyst activity. These chemisorbed materials and coke can be completely removed by the method of the present invention which involves treating the catalysts with a mixture of water vapor and nitrogen at about 60° to 250° C and thereafter, a mixture of air and nitrogen at 75° to 300° C to restore the original activity of the catalysts. This is a novel 'in-situ1 process for the removal of organic deposits, which minimizes plant down time and enables the catalysts to achieve the productivity near to that of the fresh catalyst. DESCRIPTION OF THE INVENTION The catalyst (s) which can be regenerated by the process of the present invention is known as chrome free promoted copper oxide as well as copper chromite catalyst (s), pelletized in the form of solid cylinders of 3 - 6 mm length and with the same diameter and having side crushing strength of 5 -15 kg , used in the fixed bed continuous reactors for the hydrogenation of nitro-aromatics in the vapor phase. After prolonged use in the hydrogenation process, the catalysts get deactivated due to the chemisorption of organic reactant, product, by-products, and coke on their surfaces. The deactivated catalysts can be regenerated by removing chemisorbed materials from their surfaces. The removal of the materials is carried out at 60° to 250° C by passing a mixture of water vapor and nitrogen gas through the catalyst bed (s) at a space velocity of 300 to 2000 hr_1 for a period of 20 to 50 hrs. Thereafter, as referred in Indian Patent No. 158506, oxidative gasification of the residual materials on the catalysts surfaces is done by passing a mixture of air and nitrogen with varying amount of oxygen from 0.40 to 20 % by volume at a space velocity of 300 to 11,000 hr"1 at 75° to 300 °C for 8 - 98 hrs. The 'in-situ' regeneration of the catalyses) by the novel process of the present invention restores the catalyses) activity close to mat of the fresh catalyst. The catalyses) can be processed repeatedly as described herein till it with-holds its mechanical strength. The present invention is described below by way of examples. However, the following examples are illustrative and should not be construed as limiting the scope of the invention. EXAMPLE-I Comparative Example This experiment was carried out for comparison of the activity of the fresh catalyst with that of the regenerated catalysts. The fresh, pelletised chrome free copper oxide catalyst promoted by lanthanides (30 ml. volume and 5 mm x 5 mm size) was charged in a stainless steel tubular reactor which was placed vertically and heated electrically. Since metallic copper is the active ingredient of this commercial catalyst for the hydrogenation of nitroaromatic compounds, prior to the actual use of mis material as a catalyst, it is reduced 'in-situ' by the method as described in Indian Patent No. 169449. The reduced catalyst was used to hydrogenate nitrobenzene to produce aniline at 160° - 225°C. The unreacted nitrobenzene leakage in aniline in the reactor outlet stream was found to be 5 ppm. -8 APR 2009 EXAMPLE-II The said pelletized, chrome free copper oxide catalyst as given in Example -1 was intentionally deactivated by hydrogenating nitrobenzene that contained 8% meta dinitrobenzene under the same conditions used with the fresh catalyst. The said deactivated catalyst before regeneration showed high nitrobenzene leakage of 10,000 tol 5,000 ppm during the reaction. The said deactivated catalyst was regenerated 'in-situ' by passing water vapors along with nitrogen through the catalyst bed at a space velocity of about 1,000 to 1,300 hr"1 at 180° to 220°C for 20 to 30 hrs. A part of the said catalyst regenerated in mis manner was used to hydrogenate nitrobenzene to produce aniline under the similar process conditions as described in Example I. The unreacted nitrobenzene content in aniline with die said regenerated catalyst during reaction was in the range of 1,125 - 1,350 ppm. EXAMPLE-III A part of the partially regenerated catalyst with water vapor and nitrogen as described in Example II was further treated with a mixture of air and nitrogen by the same method as described in Indian Patent No. 158506. The said regenerated catalyst was used to hydrogenate nitrobenzene under the same process parameters as referred in Example I. The unreacted nitrobenzene content in aniline during the reaction was up to 5 ppm. EXAMPLE-IV This example is given for comparison of the nitrobenzene leakage in aniline with a chrome free copper oxide catalyst deactivated under plant conditions with that of the fresh catalyst. The said pelletized, spent catalyst from the commercial aniline plant was charged in a stainless steel tubular reactor as described in Example I and was used to hydrogenate nitrobenzene under the similar process parameters as mentioned in Example I. Before regeneration, the said catalyst showed an unreacted nitrobenzene leakage of 3,000 to 5,000 ppm during the hydrogenation reaction.. EXAMPLE-V The said spent chrome free copper oxide catalyst as described in Example IV was regenerated 'in-situ' by passing water vapors and nitrogen in a similar manner as described in Example II and was used to hydrogenate nitrobenzene under the same process parameters as described in Example I. The nitrobenzene leakage in aniline during the reaction with the said catalyst was found to be 20 to 60 ppm. EXAMPLE-VI A part of the said regenerated catalyst as described in Example V was treated with a mixture of air and nitrogen by the same method as described in Ind. Patent 158506 and was used to hydrogenate nitrobenzene under the same process parameters as described in Example I. The nitrobenzene leakage in aniline during the reaction was found to be less than 5 ppm. EXAMPLE-VII A pelletized, spent copper chromite catalyst from a commercial aniline plant was regenerated by passing a mixture of water vapor and nitrogen through the catalyst bed by using the same method as described in Example II and treated further with a mixture of air and nitrogen by the method as described in Indian Patent No. 158506. The said catalyst treated by both the processes was used to hydrogenate nitrobenzene to produce aniline in the same reactor and under the same process parameters as mentioned in Example I. The nitrobenzene leakage in aniline during the reaction was found to be less than 5 ppm. EXAMPLE-VIII Regeneration in a 1:40 scale up ratio in a single tube of a multi — tubular reactor The pelletized, spent chrome free copper oxide catalyst from a commercial aniline plant was charged (1200 ml.) in a single tube pilot plant. The said catalyst was first regenerated with a mixture of water vapor and nitrogen by the similar manner as described in Example II and thereafter treated with a mixture of air and nitrogen as mentioned in Indian Patent No 158506. The regenerated catalyst by the above processes was used to hydrogenate nitrobenzene to produce aniline under the similar process conditions as described in Example I. The nitrobenzene content during the reaction with this catalyst was found to be less than 5 ppm. 8 APR 2009 WE CLAIM 1. A process for the 'in-situ' or external regeneration of spent chrome free copper oxide and copper chromite hydrogenation catalysts in pellet form, packed in a fixed bed reactor, which involves 'in-situ' removal of the chemisorbed organic deposits and coke from their surfaces comprising of passing a mixture of water vapors and nitrogen through the catalysts beds followed by oxidative gasification with a mixture of air and nitrogen: 2. A process as claimed in claim 1, wherein, the water vapor and nitrogen mixture is passed at a space velocity of 300 to 2000 hr"1. 3. A process as claimed in claim 1, wherein, the water vapor and nitrogen mixture is passed at 60 ° to 250°C. 4. A process as claimed in claim 1, wherein, the water vapor and nitrogen mixture is passed for 20 to 50 hrs. 5. A process as claimed in claim 1, wherein the mixture of air and nitrogen is passed at 75° to 300°C. 6. A process as claimed in claim 1, wherein the mixture of air and nitrogen is passed at a space velocity of 300 to 11,000 hr"1. 7. A process as claimed in claim 1, wherein the mixture of air and nitrogen is passed for 8 to 98 hrs. 8. A process as claimed in claim 1, wherein the controlled oxidation of the residual carbonaceous deposits is carried out at a constant space velocity within its range as described herein by gradually mcreasing oxygen concentration in the inlet air-nitrogen mixture from 0.40% to 20 % by volume. - 8 APR 2009 9. A process for the complete regeneration of spent chrome free copper oxide and copper chromite hydrogenation catalysts at lower temperature by the novel method as described herein with reference to the Examples I to VIII. Dated this day of 2009 For and on behalf of HINDUSTAN ORGANIC CHEMICALS LIMITED (ARVIND SHRIRAM DIDOLKAR) CHAIRMAN AND MANAGING DIRECTOR

Documents:

928-mum-2009-abstract.doc

928-mum-2009-abstract.pdf

928-MUM-2009-ANNEXURE A-(24-7-2012).pdf

928-MUM-2009-ANNEXURE B(24-7-2012).pdf

928-MUM-2009-CLAIMS(AMENDED)-(20-3-2012).pdf

928-mum-2009-claims.doc

928-mum-2009-claims.pdf

928-mum-2009-correspondence (24-6-2009).pdf

928-MUM-2009-CORRESPONDENCE(14-9-2012).pdf

928-MUM-2009-CORRESPONDENCE(24-7-2012).pdf

928-MUM-2009-CORRESPONDENCE(26-9-2012).pdf

928-mum-2009-correspondence(ipo)-(14-9-2009).pdf

928-mum-2009-description(complete).doc

928-mum-2009-description(complete).pdf

928-MUM-2009-DETAILED EXPLANATION(20-3-2012).pdf

928-mum-2009-form 1.pdf

928-mum-2009-form 18(8-4-2009).pdf

928-mum-2009-form 2(title page).pdf

928-mum-2009-form 2.doc

928-mum-2009-form 2.pdf

928-mum-2009-form 3.pdf

928-mum-2009-form 5.pdf

928-MUM-2009-REPLY TO EXAMINATION REPORT(20-3-2012).pdf