Continuous Gas‐Phase Hydroformylation of a Highly Diluted Technical C4 Feed using Supported Ionic Liquid Phase Catalysts

Abstract

The concept of supported ionic liquid phase (SILP) catalysis has been established in recent years by our group and others. Its application in continuous catalytic gas‐phase processes provides a very attractive way to bridge the gap between homogeneous and heterogeneous catalysis. In this contribution, we extend SILP hydroformylation catalysis to reactions with a highly diluted, technical C4 feed containing 1.5 % 1‐butene, 28.5 % 2‐butenes, and 70 % of inert n‐butane. To obtain the desired product, n‐pentanal, the Rh‐biphephos catalyst system was immobilized in the SILP system to allow for consecutive isomerization/hydroformylation activity. The resulting SILP catalyst material converted up to 81 % of the reactive butenes, with a residence time of 155 s in the reactor. An n‐pentanal selectivity greater than 92 % was realized for more than 500 h time‐on‐stream in the continuous gas‐phase reaction. Post‐reaction NMR studies revealed no significant loss of the phosphite ligand through ligand oxidation during the reaction.

Ionic Liquids in Catalysis

“…Shortly later, Riisager et al published the first successful example of continuous gas-phase SILP catalysis [63]. During the last years, many technically relevant examples of SILP catalysis have been published, including examples of hydroformylation [64,65], hydrogenation [66,67], enantioselective hydrogenation [68,69], water gas shift reaction [70,71], alkene metathesis [72,73], hydroamination [74] and carbonylation of methanol [75]. Additional valuable information about SILP catalysis has been collected in reviews by Riisager et al [76,77], Gu and Li [78], van Doorslaer et al [79], and Virtanen et al [80].…”

Recent Advances in Continuous Rhodium-Catalyzed Hydroformylation

“…Haumann further expanded the scope of the system by employing an Rh-diphosphiteSILP catalyst for the continuous hydroformylation of an even more challenging feedstock: the light and nonconverted fraction of a typical industrial C4 dimerization plant [48]. The feedstock has low concentration of alkenes (1.5% 1-butene and 28.5% cis/trans-2-butene) and 70% inert saturated n-butane (Scheme 3).…”

n‐butane carbonylation to n‐pentanal using a cascade reaction of dehydrogenation and SILP‐catalyzed hydroformylation

“…16,17 With the BP ligand, consecutive isomerization and hydroformylation of a highly dilute C 4 feed (reactive alkene content 30%) proceeded with a reasonable TOF of 200 h 21 and a STY of 100 kg n-pentanal m SILP 23 h…”

“…These data correspond well with the Wilkinson mechanism and recently published results for SILP catalyzed hydroformylation. 17,20,21 The overall selectivity for the linear aldehyde was greater than 96% throughout the experiment and the regioselectivity for n-pentanal, at >99.5%, was exceptionally high. 2-propyl-2-heptenal was formed by aldol condensation of two molecules of n-pentanal.…”