Discussion on the current status of catalysts in the process technology for producing o-cresol and 2,6-dimethylocresol via gas-phase alkylation of phenol with methanol
Thread Content
I would like to ask everyone: Is there currently in China any mature industrial process that uses phenol and methanol as raw materials, and gas-phase catalytic alkylation to produce o-cresol and 2,6-dimethyloxylbenzene, with Fe-M-O coprecipitated catalysts being utilized in such processes? A few years ago, I heard that Liu Zhiling and others from the Fine Chemicals Research Institute of Hunan Chemical Industry Research Institute in China had developed Fe-based catalysts and processes for this reaction. The performance of the catalyst is relatively stable. At a reaction temperature of 320–350 degrees and a catalyst load of 0.1 g phenol/g catalyst·hr, the conversion rate of phenol can reach 70%; the selectivity for o-cresol in the products is 80%, while the molar yield of o-cresol can be around 50%. In addition to o-cresol, a small amount of 2,6-dimethylocresol is also produced. It is said to be effective, with the lifespan of the developed Fe2O3-V2O5-K2O/SiO2 coprecipitated catalyst reaching over 800 hours. But later on, there were no reports of any further industrialization facilities being built and put into operation. I wonder what the reason is? What other “technical bottlenecks” and “technical challenges” remain unsolved? Those who are familiar with this area please provide detailed information, so as to facilitate further \"improvement\" of this technology and its eventual adoption in industrial applications. Thank you so much!
Basic production process of o-cresol and 2,6-dimethylphenol: Using phenol as the raw material, and methanol as the hydrocarbonating agent, o-cresol can be produced in the presence of a catalyst. A fixed-bed tubular reactor is used, with a reaction temperature of 335–360°C. The catalyst can be aluminum oxide or magnesium oxide, or it can also be vanadium pentoxide-iron oxide. In the reaction mixture obtained from the reactor, there are methanol, phenol, o-cresol, and 2,6-dimethylphenol. Fractionation is carried out: methanol and water are distilled off first, followed by the recovery of phenol. Then, o-cresol is purified through distillation. The distillation is performed at a pressure of 0.098 MPa and a temperature of 101–102°C; o-cresol is distilled off at the top of the tower, with a purity of over 99.5%, while 2,6-dimethylphenol remains at the bottom of the tower. This production process is a gas-phase method, which is mature and features high yields. Catalysts tend to be composite types; catalysts with a single catalytic component are no longer the mainstream. Additionally, there are some liquid-phase production processes; their maturity is satisfactory, but their relative production efficiency is lower than that of the gas-phase method.
Very good. But I wonder how many domestic industrial plants use this vapor-phase method to produce o-cresol? What is the overall scale? It seems like it can’t be found online?