Heterogeneously catalyzed etherification of glycerol to diglycerol over calcium–lanthanum oxide supported on MCM-41: A heterogeneous basic catalyst

• Solventless etherification of glycerol to diglycerol.
• Heterogeneous basic catalyst based on calcium–lanthanum oxide supported on MCM-41.
• Ca1.6La0.6/MCM-41 showed glycerol conversion of 91% and diglycerol yield of 43%.
• Correlation between catalyst activity and leaching of metal oxides during the reaction.
• Production of αβ isomer as the favored diglycerol product during the reaction.

The catalytic etherification of glycerol using calcium–lanthanum oxide supported on MCM-41 as a stable heterogeneous basic catalyst was investigated. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were when characterized using different techniques. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca1.6La0.6/MCM-41 catalyst resulted in the highest glycerol conversion of 91% at the diglycerol yield of 43%. The distribution of diglycerol isomer in the etherification of glycerol was studied, and the value of the sum of two dimers (ββ′ + αβ = 67%) was found to be higher than that of αα′ dimer (33%) after 8 h of reaction. Thus, the major reaction occurred inside the porous area instead of the external surface area.

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