FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10, Rule 13)
1. TITLE OF THE INVENTION: A PROCESS FOR THE UTILIZATION OF OFF GAS
HYDROGEN WITHOUT PURIFICATION FOR ANILINE PRODUCTION

2. APPLICANT® (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 tollowing specification particularly describes the invention and the manner in which ft is to be performed:

PRIOR ART
Aniline finds applications in the manufacture of a wide variety of chemicals such as polymers, rubber, agricultural chemicals, dyes, pigments etc. It can be produced on commercial scale by catalytic reactions of chlorobenzene and aqueous ammonia, ammonolysis of phenol, and reduction of nitrobenzene (Hawley's Condensed Chemical Dictionary, 11 Edition, Nostrand Reinhold Company, 1987, p 81). Catalytic liquid phase hydrogenation of nitrobenzene is carried out at 80° to 250 °C under pressure with aniline yields of 98 to 99% (Ulknarai's Encyclopedia of Industrial Chemistry, Volume A2, P 305). hi a liquid phase continuous process, aniline was produced by hydrogenating nitrobenzene over finely divided Ni on Kieselghur (US Patent 3270057, 1966). The catalytic vapor phase reductions of nitrobenzene were carried out in fixed or fluidized beds by using non-noble metal catalysts containing Cu or Ni supported on a carrier. In Lonza Process, aniline has been produced in vapor phase by hydrogenating nitrobenzene in a fixed bed reactor at 150° to 300 °C in presence of a Cu catalyst supported on pumice at a gauge pressure of 200 to 1500 kPa (US Patent 3636152, 1972). hi BASF Process, the hydrogenation of nitrobenzene was carried out in vapor phase fluidized bed with a silica supported Cu catalyst promoted with compounds of Cr, Zn or Ba at 250° to 300 °C under 400 to 1000 kPa pressure where aniline yield was more than 99% (US Patent 3136818, 1964). In a latest publication, aniline has been produced by using copper oxide catalysts with La and Ce oxides as promoters and oxides of Ca, Al and Si as supports. (Indian Patent Application No. 2010/MUM/2008 dated 18/9/2008).
It is seen in almost all the aniline manufacturing processes in continuous mode that only pure hydrogen is used for the hydrogenation of nitrobenzene. Purification of raw hydrogen obtained from naphtha cracking conventionally requires purification units such as a shift converter for CO to C02 conversion and a Pressure Swing Absorber for absorption of impurities like CO, CO2 and CH4 . These units involve fixed as well as running costs and add to the product cost Further, hydrogen is passed in far excess of nitrobenzene, some times as high as 20:1 mole instead of stoichiometric requirement of 3:1 mole.

The novelty of the present invention is utilization of off gas hydrogen without purification to economically produce aniline in fixed bed reactors in vapor phase at 160° to 225° C and at atmospheric pressure. Typically, off gas hydrogen is obtained from exit gases of industries that produce formaldehyde from methanol rich processes using silver catalysts or from those involving oil cracking processes for producing aromatic hydrocarbons. The formaldehyde process off gas contains about 25% hydrogen and mat of oil cracking process about 85% hydrogen.
OBJECTIVE OF THE INVENTION
The objective of the present invention is to utilize off gas hydrogen without purification from the industrial processes to hydrogenate nitrobenzene to economically produce aniline in vapor phase fixed bed reactors by using conventional catalysts. This is an effort to utilize waste hydrogen to produce value added products.
SUMMARY OF THE INVENTION
This invention relates to a process for the utilization of off gas hydrogen without purification from the industrial processes to economically produce aniline from nitrobenzene in vapor phase fixed bed reactors. The catalyst which has been used for the said process is chrome free copper oxide containing La and Ce oxides as promoters with compounds of Ca, Al and Si as supports. This catalyst is already being used in conventional aniline process using pure hydrogen. A mixture of a simulated off gas composition of a formaldehyde process consisting of hydrogen and nitrogen, and nitrobenzene vapors in the hydrogen to nitrobenzene to nitrogen molar ratio of 5 : 1 : 21 to 20:1:79 was passed through the catalyst beds at a space velocity of 500 to 2000 hr-1 at 160° to 225°C. The aniline in outlet streams of the reactor was found to be 92.55% to 99.43%. Similarly, a mixture of an off gas from an oil cracking process containing about 85% hydrogen and about 15%C1toC6+ hydrocarbons, and nitrobenzene vapors with a hydrogen to nitrobenzene to hydrocarbon molar ratio of 18 : 1: 3.18 to 23.73 : 1 : 4.19 was passed through the said catalyst beds at the said space velocity and temperature. The aniline in outlet streams of the reactor was found to be 97.93% to 98.03%.

DESCRIPTION OF THE INVENTION
The present invention provides a process to utilize off gas hydrogen without purification from industrial processes in which hydrogen content varies from 25% to 85% along with nitrogen or C1 to C6+. hydrocarbons depending upon its source to economically produce aniline by hydrogenating nitrobenzene. The mixture of the said off gases and nitrobenzene vapors is passed through the catalyst beds at a space velocity of about 500 to 2000 hr_1 at 160° to 225° C in fixed bed reactors. The mote ratio of hydrogen to nitrobenzene to nitrogen for formaldehyde process off gas varies from 5:1:21 to 20:1:79. Similarly, the hydrogen to nitrobenzene to hydrocarbon mole ratio for off gas from oil cracking process varies in the range 18: 1 : 3.18 to 23.73 : 1 : 4.19 . The reactor outlet streams contain about 92.55% to 99.43 % aniline widi the off gas hydrogen from formaldehyde process and 97.93% to 98.03 % from the oil cracking source. The present invention is further described below by way of examples. However, these examples are illustrative and should not be construed as limiting the scope of this invention.
EXAMPLE -1
Comparative Example
This experiment was carried out for comparison of the aniline yield under standard process conditions. A fresh, pelletised chrome free copper oxide catalyst promoted with oxides of La and Ce and supported on compounds of Ca, Al and Si (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 catalyst for the hydrogenation of nitro aromatic compounds, prior to the actual use of this catalyst, it is reduced in-situ by the method as described in Indian Patent No. 169449. A mixture of pure hydrogen and nitrobenzene vapors in the mole ratio of 14.73 : 1 was passed through the said reduced catalyst bed at a space velocity in the range 500 to 1200 h"1 at 160° to 225° C. The aniline in the reactor outlet stream was 99. 90%.

EXAMPLE - H
Impure hydrogen composition similar to that in off gas from formaldehyde process using silver catalyst was simulated by mixing hydrogen wim nitrogen. Subsequently, nitrobenzene vapors were introduced in the said mixture to give a gaseous mixture containing hydrogen, nitrobenzene and nitrogen in the molar ratio of 21.47 : 1: 42.93. This was passed through the said catalyst bed at the said space velocity and temperature as described in Example I. The aniline in reactor outlet streams was found to be 97.46 %.
EXAMPLE-HI
A gaseous mixture as described in Example - II of hydrogen, nitrobenzene and nitrogen in the molar ratio of about 11.75 : 1: 46.98 was passed through the said catalyst bed at the said space velocity and temperature as described in Example -1. The aniline in the reactor outlet streams was found to be 99.43%.
EXAMPLE-IV
A gaseous mixture as described in Example - II of hydrogen, nitrobenzene and nitrogen in the molar ratio of about 12.83 : 1: 51.32 was passed through the said catalyst bed at the said space velocity and temperature as described in Example -1. The aniline in the reactor outlet streams was found to be 99.72%.
EXAMPLE-V
A gaseous mixture as described in Example - II of hydrogen, nitrobenzene and nitrogen in the molar ratio of about 5.32 : 1: 21.31 was passed through the said catalyst bed at the said space velocity and temperature as described in Example - I. The aniline content in the reactor outlet streams was found to be 92.55%.

EXAMPLE-VI
An exit off gas of an industrial oil cracking process for producing aromatic hydrocarbons was used. The off gas containing about 85 % hydrogen and about 15 % C1 to C6+ hydrocarbons was mixed with nitrobenzene vapors in the hydrogen to nitrobenzene to hydrocarbon molar ratio of 18:1: 3.18 to 23.73 : 1: 4.19 and was passed through the catalyst bed at the said space velocity and temperature as described in Example - I. The aniline content in the reactor outlet streams was found to be 97.93% to 98.03 %.

We claim:
1. A process for the hydrogenation of nitro aromatic compounds with exit off gas hydrogen with out purification of the industrial processes involving typically formaldehyde or aromatic hydrocarbons to produce aniline in vapor phase continuous mode in fixed bed reactors using conventional chrome free copper oxide catalysts :
2. A process as claimed in claim 1, wherein the hydrogen content in the off gas stream of industrial processes varies from 15% to 90% by volume, preferably 25% to 85 %.
3. A process as claimed in claim 1, wherein the hydrogen content varies from 5 to 30 moles with respect to one mole of nitrobenzene.
4. A process as claimed in claim 1, wherein the mixture of hydrogen, nitrobenzene and nitrogen or hydrocarbon is passed at a space velocity of 500 to 2000 hr"1, preferably 900 to 1500 hr1
5. A process as claimed in claim 1, wherein the mixture of hydrogen, nitrobenzene and nitrogen or hydrocarbon is passed at 160° to 225° C.
6. A process as claimed in claim 1, wherein the said catalyst is chrome free copper oxide promoted with the oxides of La and Ce, and supported on the compounds of Ca, Al and Si.
7. A process for the hydrogenation of nitroaromatic compounds with exit off gas hydrogen containing nitrogen or hydrocarbons as impurities depending upon its source to produce aniline as described herein with reference to the Examples I to VI.