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Selective C−C Hydrogenolysis of Alkylbenzenes to Methylbenzenes with Suppression of Ring Hydrogenation
Author(s) -
Yanatake Shin,
Nakaji Yosuke,
Betchaku Mii,
Nakagawa Yoshinao,
Tamura Masazumi,
Tomishige Keiichi
Publication year - 2018
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201801118
Subject(s) - hydrogenolysis , chemistry , alkylbenzenes , ethylbenzene , catalysis , toluene , cumene , heterogeneous catalysis , benzene , inorganic chemistry , organic chemistry
Selective reduction of alkylbenzenes, which are supplied by refining heavy hydrocarbons, to methylbenzenes by selective C−C hydrogenolysis was accomplished by Ru/CeO 2 catalyst. Hydrogenolysis of ethylbenzene was carried out with gas‐phase fixed‐bed flow reactor and various noble metal catalysts. The catalyst with high Ru loading (4 wt%) on CeO 2 support pre‐calcined at high temperature (1073 K; Ru(4)/CeO 2 1073 catalyst) showed both good activity and selectivity to toluene. The yield of toluene reached 65 %‐C in the conditions of 533 K and H 2 partial pressure of 0.075 MPa. Hydrogenolysis of other alkylbenzenes including p ‐ethyltoluene, propylbenzene and cumene was also carried out. Hydrogenolysis of C aryl ‐C alkyl bond and hydrogenation of benzene ring was slow in all substrate cases. Hydrogenolysis of p ‐ethyltoluene can give p ‐xylene as the main product (highest yield: 53 %‐C). These high yields of methylbenzenes make a marked contrast to the traditional bifunctional hydrocracking systems which preferably dissociate C aryl ‐C alkyl bond in alkylbenzenes. Characterization of Ru catalysts suggests that the block‐shaped Ru particles with small size (<2 nm) in Ru(4)/CeO 2 1073 give good catalytic performance. Too strong interaction between Ru species and CeO 2 support induced by decreasing the loading amount rather gives ring‐hydrogenation activity and decreases methylbenzenes selectivity.