Vapor-phase ethanol carbonylation with heteropolyacid-supported Rh

Abstract

a b s t r a c tEthanol carbonylation is a potential route to valuable C3 products. Here, Rh supported on porous, Cs-exchanged heteropolyacid Cs 3 PW 12 O 40, is demonstrated as an effective catalyst for vapor-phase ethanol carbonylation, with higher selectivity and conversion to propionates than existing catalysts. Residual acidity or a Mo polyatom was strongly detrimental to yields. Propionate selectivity was maximized at 96% at 170°C and with added H 2 O. The catalyst displayed stable selectivity over 30 h on stream and up to 77% conversion. Ethyl iodide is a required co-catalyst but at levels as low as 2% relative to ethanol. XPS and in situ XANES indicate partial Rh reduction, consistent with the formation of low-valent reactive intermediates and slow deactivation through formation of Rh nanoparticles. With further optimization and understanding, these Rh/heteropolyacid catalysts may lead to stable and selective catalysts for the production of propionates through ethanol carbonylation.

Quaternary phosphonium polymer-supported dual-ionically bound [Rh(CO)I3]2– catalyst for heterogeneous ethanol carbonylation

“…Thus, higher pressure favors the formation of propionyl products and enhances the carbonylation activity. Notably, the activity of 436 h -1 achieved in the reaction over Rh-TPISP was much higher than that previously reported for corresponding homogeneous and heterogeneous systems [38,[49][50][51], accompanied by a satisfactory There is little research on the stability of catalysts for ethanol carbonylation [50,51]; thus, we studied the stability of Rh-TPISP for carbonylation, as depicted in Fig. 9.…”

“…Homogeneous ethanol carbonylation is a single-step selective process for generating PA [38][39][40][41], but the homogeneous catalysis of ethanol carbonylation is much less effective than that of methanol carbonylation [42][43][44][45][46][47][48], and the development of heterogeneous ethanol carbonylation processes remains challenging because of the low stability of the catalysts. Nefedov et al [49] and Notesteina et al [50,51] reported valuable studies on heterogeneous ethanol carbonylation. The Rh species were supported on a zeolite, with a highest TOF of approximately 70 h -1 at 1 atm and 473 K, and the Rh species were supported on Cs heteropolyacid with a maximal propionate selectivity of 96% under 1 atm at 473 K with the addition of water.…”

Kinetic study of carbonylation of ethanol using homogeneous Rh complex catalyst

“…A number of catalysts can used for ethanol carbonylation, such as Rh, Ru, Co, Pd and Ir compounds. [ 7–13 ] However, except Rh, these catalysts require extremely high pressures (~40 MPa) and suffer from poor yields. Therefore, the carbonylation of ethanol with rhodium complex as catalyst can be carried out under more mild conditions and has higher activity and selectivity due to its high activity.…”

On the Spatial Design of Co-Fed Amines for Selective Dehydration of Methyl Lactate to Acrylates

“…6 In particular, organic bases, such as ammonia, alkyl amines, and pyridine [7][8][9][10] bind on Brønsted acid sites (BAS) even at elevated temperatures above 160 ℃, typical for gas-phase reactions. 3,[11][12][13] However, ammonia and pyridine adsorb on both Lewis and Brønsted acid sites. 7,14 Selective BAS adsorption can be obtained using 2,6-substituted pyridines with steric constraints around the nitrogen atom.…”