Selective C−C Hydrogenolysis of Alkylbenzenes to Methylbenzenes with Suppression of Ring Hydrogenation

Abstract

Selective reduction of alkylbenzenes, which are supplied by refining heavy hydrocarbons, to methylbenzenes by selective CÀC 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 precalcined 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.[a] S.

Site-Selective Polyolefin Hydrogenolysis on Atomic Ru for Methanation Suppression and Liquid Fuel Production

“…S2 ). The strong metal–support interaction (SMSI) between Ru and CeO 2 should contribute to dispersing Ru atoms [ 32 , 33 ], and such an SMSI effect would also enhance the catalytic stability (see detailed discussion in catalysis part).…”

Structure-guided insights into non-catalytic (α-hydroxy)alkylation of olefins with alcohols

“…44 Toluene was a usual product of styrene reaction under all reaction conditions A–D (lines 6–11, Table 2; lines 1–3, Table 3). This product of a one-carbon chain-shortened initial molecule is not an experimental artefact, but a conventional product co-produced from ethylbenzene by hydrogenolysis of its CH 2 –CH 3 bond (Scheme 2), for example under catalysis by Ru/CeO 2 at 260 °C 45 or Ni/SiO 2 at 165 °C. 46 Thus, at 350 °C in alcohol, toluene was a normal by-product of olefinic CC transfer hydrogenation of styrene to ethylbenzene followed by transfer hydrogenolysis of the C(sp 3 )–C(sp 3 ) bond of its ethyl substituent.…”

Mechanism of Formation of Highly Dispersed Metallic Ruthenium Particles on Ceria Support by Heating and Reduction

“…This Ru/CeO 2 catalyzes regioselective hydrogenolysis of squalane, , and the regioselectivity to C secondary –C secondary bonds above C tertiary –C secondary or C tertiary –C primary bonds is higher than that of Ru/CeO 2 and Ru/SiO 2 with larger Ru metal particles. The highly dispersed Ru/CeO 2 also catalyzes regioselective hydrogenolysis of hydrogenated botryococcene, selective hydrogenolysis of alkylbenzenes to methylbenzenes, and selective hydrogenation of amide to alcohols . As related catalysts, Ru–MO x /SiO 2 (M: metal) catalysts were also tested for regioselectivity of squalane .…”