Jian-Ping Shen

Shape-selective synthesis of 4,4′-dimethylbiphenyl. 1. Methylation of 4-methylbiphenyl over modified zeolite catalysts

Methylation of 4-methylbiphenyl with methanol was carried out using zeolites HY, HM, and HZSM-5 as catalysts under fixed-bed down-flow conditions. HY and HM display no shape selectivity, but HZSM-5 shows moderate selectivity to the target product, 4,4′-dimethylbiphenyl (4,4′-DMBP) under proper reaction conditions. Modification of the surface of HZSM-5 zeolite can improve the selectivity to 4,4′-DMBP, especially the simultaneous modification of external and internal surface with inorganic P compound. The selectivity to 4,4′-DMBP can be increased to as high as 65% over the HZSM-5 modified with a small amount of ammonium hydrogen phosphate.

Shape-selective Fe-MFI catalyst for synthesis of 2,6-dimethylnaphthalene by methylation with methanol

The present study deals with shape-selective methylation of naphthalene for synthesis of 2,6-dimethylnaphthalene (2,6-DMN), and focuses on the Fe-MFI (Fe-ZSM-5) catalyst prepared by isomorphous substitution using Fe compounds and ZSM-5, which led to a highly shape-selective catalyst formulation for 2,6-DMN synthesis. Results with modified ZSM-5 by isomorphous substitution with Ti and Co, by ion exchange with Fe as well as acid treatment of ZSM-5 are also shown for comparison. The best Fe-ZSM-5 formulations used under suitable conditions can lead to shape-selective methylation of naphthalene with methanol, with the 2,6-/2,7-DMN ratio and 2,6-DMN/DMNs percentage reaching as high as 2.2 and about 60%, respectively.

Effects of hydrothermal treatment conditions on the catalytic activity of HZSM-5 zeolites in the methylation of 4-methylbiphenyl with methanol

The objective of this work is to study the effects of hydrothermal treatment conditions on the methylation of 4-methylbiphenyl (4-MBP) with methanol under fixed-bed down-flow conditions. The results show that hydrothermal treatment temperature has a marked effect on the activity and selectivity in the methylation of 4-MBP with methanol. 4-MBP conversion decreases and the selectivity to 4,4′-dimethylbiphenyl (4,4′-DMBP) increases with an increase in the hydrothermal treatment temperature. The optimal temperature range is between 400 and 550 °C. After hydrothermal treatment, the catalytic selectivity to 4,4′-DMBP is up to 70%, while the 4-MBP conversion is about 12%. The high selectivity over hydrothermally treated ZSM-5 largely results from the suppression of 4,4′-DMBP secondary reactions such as isomerization and dealkylation, as demonstrated by the reaction of 4,4′-DMBP as reactant over hydrothermally treated ZSM-5 and the parent zeolite.

Novel shape-selective catalysts for synthesis of 4,4′-dimethylbiphenyl

Shape-selective methylation of 4-methylbiphenyl was studied using zeolites HY, HM and HZSM-5 under the down-flow conditions. HY and HM display no shape selectivity, but HZSM-5 shows moderate selectivity to the target product, 4,4′-dimethylbiphenyl (4,4′-DMBP). Increasing the crystal size and modifing the surface of HZSM-5 zeolite can improve the selectivity to 4,4′-DMBP. The modification of external and internal surface with inorganic P compound was found to be very effective. The selectivity to 4,4′-DMBP can be increased to as high as 65% over the HZSM-5 modified with a small amount of ammonium hydrogen phosphate.