Potassium and 12‐tungstophosphoric acid loaded alumina as heterogeneous catalyst for the esterification as well as transesterification of waste cooking oil in a single pot

Gas-Phase Catalytic Dehydration of Glycerol with Methanol to Methyl Glyceryl Ethers over Phosphotungstic Acid Supported on Alumina

Glycerol can be dehydrated with methanol to produce methyl glyceryl ethers as biologicals and diesel fuel additives. Considering the high efficiency of mass transfer and product separation in the gas-solid catalytic process, a fixed-bed continuous-flow reactor was used to carry out the catalyst evaluation test of the process at 564 K. Compared with zirconium sulfate, lanthanum nitrate, and ammonium molybdate, phosphotungstic acid exhibits a higher target product selectivity. Through loading experiments, it was found that the optimal loading fraction of phosphotungstic acid on alumina is 10 wt %. After the alumina carrier is impregnated with nitric acid, the selectivity and yield of monomethyl glycerol ether can be effectively improved, and it has little effect on other products. A test of the addition amount of cerium nitrate as a promoter was carried out. It was shown in the test that when the addition amount of cerium nitrate is 10 wt %, the catalyst life increases from 2 to 3.5 h and the selectivity of dimethyl glycerol ether increases to 54.51%, which is twice the original. However, the selectivities of monomethyl glycerol ether and trimethyl glycerol ether decrease by one-half each. Through catalyst characterization, it was shown that carbon deposition on the catalyst surface is one of the reasons for catalyst deactivation.

Bimetallic MOF-Derived Synthesis of Cobalt-Cerium Oxide Supported Phosphotungstic Acid Composites for the Oleic Acid Esterification

The impregnation of phosphotungstic acid (HPW) with porous cobalt-cerium oxide (HPW@CoCeO) has been prepared by pyrolysis of CoCe-MOF and used for the production of methyl oleate from oleic acid and methanol. FTIR, XRD, SEM, TEM, N2 adsorption/desorption, and NH3-TPD were characterized for the prepared composites. Simultaneously, the effects of reaction time, substrate molar ratio, temperature, and catalyst loading on catalytic activity were highlighted, and the conversion of 67.2% was reached after 4 h at 60°C. Importantly, HPW@CoCeO was reusabe and reused more than eight times, and the oleic acid conversion could be maintained at 61.8% without significant activity loss. Thus, the HPW@CoCeO composite could be used as acid catalysts for sustainable energy production.