Conversion of MeOH and Toluene into Styrene and Ethylbenzene Using Composite Catalysts Containing MeOH Dehydrogenation Components

Abstract

Scheme 1. Coupling reaction of methanol dehydrogenation and side-chain alkylation of toluene over composite catalysts. Na 2 B 4 O 7 and CsX were selected as model catalysts.

Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

“…It should be mentioned here that, although the catalytic activity of 0.15 Fe/CsX-I is lower than the literature-reported ZrB 2 O 5 -or BPO 4 -modified CsX catalysts [9,19], it is still a relatively active catalyst in comparison with other additive-modified CsX catalysts, like Cs 2 O/CsX [7], Na 2 B 4 O 7 /CsX [17], and ZnO/CsX [39], suggesting that Fe(NO 3 ) 3 could functionalize as an effective additive to improve the catalytic performance of the ion-exchanged CsX catalyst. A undesirable feature of the Fe(NO 3 ) 3 -modified CsX catalyst is that it exhibits relatively low selectivity to styrene, and high selectivity to ethylbenzene.…”

“…Hattori and coworkers reported that metal borate-modified CsX showed improved catalytic activity and selectivity compared to styrene owning to the ability of borates to selectively form formaldehyde from methanol [7,9]. Han et al [17] gave a similar speculation after studying the side-chain alkylation reaction over composite catalysts composed of CsX and sodium borate (Na 2 B 4 O 7 ) or CuO/SiO 2 . In another work reported by Wieland et al [2], they proposed that impregnating boric acid on CsX could effectively promote the side-chain alkylation activity by neutralizing some unfavorable strong basic sites, which are the main active centers for rapidly decomposing methanol to byproducts like CO and H 2.…”

“…For 0.15 Fe/CsX-II, the obvious decrease in basic sites should be an indication that FeCl 3 has a stronger ability to neutralize or cover more basic sites in the CsX catalyst [21,23]. Previous literature results already revealed that the basic sites of CsX zeolites are the main active sites for the side alkylation reaction of toluene with methanol [15][16][17][24][25][26]. Therefore, the significant decrease in catalytic activity of the FeCl 3 -modified CsX should be due mainly to the considerable loss in the number of basic sites.…”

“…As a representative catalyst system, Cs ion-exchanged X zeolites (CsX) received considerable attention for their relatively high catalytic activity and selectivity to styrene [8,9,15]. More interestingly, it was found that the catalytic performance of CsX may be further improved by modification with some additives [9,16,17].…”

Industrial catalysis: Strategies to enhance selectivity

“…3(a)) [24]. The produced formaldehyde acts as the actual alkylating reagent [25]. During alkylation, a couple of side-reactions occur.…”