Structures and reaction mechanisms of glycerol dehydration over H-ZSM-5 zeolite: a density functional theory study

Citations Over TimeTop 10% of 2011 papers

Abstract

The initial stage of glycerol conversion over H-ZSM-5 zeolite has been investigated using density functional theory (DFT) calculations on an embedded cluster model consisting of 128 tetrahedrally coordinated atoms. It is found that glycerol dehydration to acrolein and acetol proceeds favourably via a stepwise mechanism. The formation of an alkoxide species upon the first dehydration requires the highest activation energy (42.5 kcal mol(-1)) and can be considered as the rate determining step of the reaction. The intrinsic activation energies for the first dehydration are virtually the same for both acrolein and acetol formation, respectively, suggesting the competitive removal of the primary and secondary OH groups. A high selectivity to acrolein at moderate temperatures can be attributed to the selective activation of the stronger adsorption mode of glycerol through the secondary OH group and the kinetically favoured subsequent consecutive steps. In addition, the less reactive nature of acrolein relative to acetol precludes it from being converted to other products upon conversion to glycerol. In accordance with typical endothermic reactions, the forward rate constant for glycerol dehydration significantly increases with increasing reaction temperature.

Related Papers

• → Fast and efficient synthesis of SSZ-13 by interzeolite conversion of Zeolite Beta and Zeolite L(2019)65 cited
• → Estimation of activation energy for desorption of low-volatility dioxins on zeolites by TPD technique(2003)48 cited
• Research Progress of zeolite synthesis from kaolin(2010)
• Polysulfone으로 제올라이트 A를 고정화한 방사성 물질제거용 PS-zeolite 비드 제조(2015)
• 쳔연 Zeolite ( 제올라이트 ) 를 이용한 중금속 흡착제의 개발(1991)