Catalysis Today, Vol.332, 20-27, 2019
Gas-phase dehydration of glycerol to acrolein catalyzed by hybrid acid sites derived from transition metal hydrogen phosphate and meso-HZSM-5
The dehydration of glycerol to acrolein is a useful approach for the value-added conversion of bio-diesel derived glycerol. To improve the acrolein yield, the transition metal hydrogen phosphates/meso-HZSM-5 hybrid catalysts were synthesized and examined for glycerol dehydration. The commercial HZSM-5 firstly treated with alkaline for introducing mesoporosity and investigated the glycerol dehydration over the various composite catalysts prepared by monohydrogen phosphates (CuHPO4, Mo1/3HPO4, ZnHPO4, NiHPO4, MnHPO4) supported on meso-HZSM-5. The hybrid catalysts presented for improvement of strong acid sites and acrolein yield. Additionally, the studies on the hydrogen number in nickel-hydrogen phosphates demonstrated that the NiHPO4/meso HZSM-5 exhibited higher acrolein yield than Ni3/2PO4/meso-HZSM-5 and Ni1/2H2PO4/meso-HZSM-5 catalyst systems. The activities of the composite catalysts significantly influenced by the pore characteristics of support, types of transition metal hydrogen phosphates, amount and strength of acid sites. The proper arrangement of hybrid catalyst with strong Lewis acid sites is a viable and effective method for design functional solid acid catalyst and develops their catalytic performance in glycerol dehydration to acrolein.