Diatomite Stabilized KOH: An Efficient Heterogeneous Catalyst for Cyclopentanone Self‐condensation

Abstract

Aldol condensation of cyclopentanone is an attractive reaction for bio‐jet fuel production. KOH is an efficient homogeneous catalyst for aldol condensation but suffering the problem of separation. In this paper, a heterogeneous catalyst, diatomite stabilized KOH (KOH/diatomite) was prepared in a simple way (dry‐mixed impregnation process), and exhibited good activity (overall yield: 85.0 %) and reusability. To clarify the support effect of diatomite, KOH/SiO2 catalyst was also prepared. According to characterizations of these two catalysts, we suggest that the excellent catalytic activity of KOH/diatomite can be attributed to the formation of K−O−Si bond. In addition, the impurity elements existed in diatomite (e. g. CaO, Na2O, Al2O3) and higher BET surface areas may also benefit to this reaction. This study provides a new possibility for converting homogeneous catalyst (KOH) to heterogeneous catalyst (KOH/diatomite). In this way, KOH/diatomite performed excellent catalytic activity and exhibited stable reusability, which can avoid the problem of separation and pollution.

Cyclopentanone Self-Aldol Condensation by Ball-Milling Method: Optimization Using Response Surface Methodology (RSM) and Life Cycle Assessment (LCA)

“…The waste liquid was produced during this process due to the loss of ethanol (10%). For the magnetic stirring method, the optimized condition (4 g of cyclopentanone, 0.25 g of 25 wt % KOH­(aq)) with 93.5% product yield was selected as the set point, which was reported in our previous work . The preparation of the KOH aqueous solution was considered part of the system boundary.…”

“…For the magnetic stirring method, the optimized condition (4 g of cyclopentanone, 0.25 g of 25 wt % KOH(aq)) with 93.5% product yield was selected as the set point, which was reported in our previous work. 11 The preparation of the KOH aqueous solution was considered part of the system boundary. Prior to cyclopentanone selfcondensation, KOH and water were premixed with a 1:3 mass ratio and no weight loss was considered during this process.…”

“…8 It can go through a self-condensation reaction, and dimer (C 10 compound) and trimer (C 15 compound) can be generated with a high yield (80%). 9−11 Various heterogeneous catalysts have been reported in this reaction, including hydrotalcite-based catalysts, 9 solid metal oxides, 10,12 diatomite-stabilized KOH, 11 and metal−organic framework (MOF)-derived catalysts. 13,14 Yang et al used MgAl hydrotalcite and LiAl hydrotalcite to catalyze cyclopentanone self-condensation, and a high yield (>80%) of the dimer was achieved under optimized conditions.…”

“…Therefore, the synthesis of sustainable fuel from biomass-derived compounds has gained constant interest. − Cyclopentanone is a biomass-derived platform molecule that could be generated by the hydrolysis–dehydration of hemicellulose . It can go through a self-condensation reaction, and dimer (C 10 compound) and trimer (C 15 compound) can be generated with a high yield (80%). − Various heterogeneous catalysts have been reported in this reaction, including hydrotalcite-based catalysts, solid metal oxides, , diatomite-stabilized KOH, and metal–organic framework (MOF)-derived catalysts. , Yang et al used MgAl hydrotalcite and LiAl hydrotalcite to catalyze cyclopentanone self-condensation, and a high yield (>80%) of the dimer was achieved under optimized conditions . Deng et al reported a high selectivity (98.1%) of dimer in the presence of MOF-encapsulated phosphotungstic acid catalyst .…”

Isobaric Vapor–Liquid Equilibria for the Binary System of Adiponitrile and Cyclopentanone at 5 and 10 kPa

“…Cyclopentanone is one of the byproducts that are formed by the decarboxylation of adipic acid and hold a certain proportion in the raw product. 2 Considering the instability of cyclopentanone at higher temperatures than 200 °C, 3 the operating temperature of the separation system needs to be set at a low condition. To design and optimize the separation and purification processes, the vapor−liquid equilibrium (VLE) data of adiponitrile and cyclopentanone at low pressure is necessary.…”