# US 8,772,552 B2 · Process for the selective hydroxylation of benzene with molecular oxygen

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- Number: US 8,772,552 B2
- Document ID: US8772552B2
- Status: Granted
- Kind: B2
- Application number: 13/623,653
- Filed: 2012-09-20
- Published: 2013-04-18
- Granted: 2014-07-08
- Earliest claimed: 2011-09-22
- Assignees: Council of Scientific and Industrial Research
- Applicants: Council of Scientific & Industrial Research
- Inventors: Rajaram Bal; Shubhra Acharyya Shankha; Shilpi Ghosh; Bipul Sarkar; Karan Singh Rawat; Chandrashekar Pendem
- Web page: https://patentgrep.com/patent/US8772552B2

## CPC

- C07C 37/58: by oxidation reactions introducing directly hydroxy groups on a =CH-group belonging to a six-membered aromatic ring with the aid of molecular oxygen
- Y02P 20/52: using catalysts, e.g. selective catalysts
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The present invention provides an improved process for the selective hydroxylation of benzene. The process provides a direct single step selective vapor phase hydroxylation of benzene to phenol using molecular oxygen (air) over Cu—Cr oxide catalysts. The process provides benzene conversion of 10 to 45% and selectivity for phenol up to 100%.

## Claims

### Claim 1

A process for making phenol comprising the step of selectively hydroxylating benzene with molecular oxygen over solid catalysts which comprises reacting benzene with air in the pressure range of 1-5 MPa, at a temperature of 150-450° C. with a liquid hourly space velocity (LHSV, benzene feed/g catalyst/hour) in the range of 20 to 400 for a period of 1-30 hrs to obtain phenol, wherein the solid catalyst is Cu—Cr oxide.

### Claim 2 (depends on 1)

A process as claimed in claim 1, wherein the molar ratio of Cu to Cr of the catalyst varied in the range of 0.1 to 0.5.

### Claim 3 (depends on 1)

A process as claimed in claim 1, wherein the air pressure is in the range of 2-5 MPa.

### Claim 4 (depends on 1)

A process according to claim 1, wherein the reaction temperature is in the range 200-400° C.

### Claim 5 (depends on 1)

A process as claimed in claim 1, wherein the liquid hourly space velocity (LHSV) is in the range 30 to 300.

### Claim 6 (depends on 1)

A process as claimed in claim 1, wherein the reaction time used is in the range 2-30 h.

### Claim 7 (depends on 1)

A process as claimed in claim 1, wherein the conversion of benzene is in the range of 1-42%.

### Claim 8 (depends on 1)

A process as claimed in claim 1, wherein the selectivity of the phenol obtained in the range of 50-100%.

### Claim 9 (depends on 1)

A process as claimed in claim 1, wherein the molecular oxygen is provided from air.