Deactivation Aspects of Methanolysis Catalyst Based on CaO Loaded on Mesoporous Carrier

Abstract

With the depletion of fossil fuels as a source for fuels and energy, the share of energy supplied by renewable resources such as biomass can be expected to increase in the anticipated future. Biodiesel, composed of fatty acid methyl esters (FAME), is one of the renewable alternative to fosil fuels which is most common obtained in catalyzed transesterification reaction of triacylglycerols (TAG). Naydays, the most promicing process is considered continuous basic heterogeneously-catalyzed methanolysis of sustainable sources of TAG. Heterogeneouslycatalyzed process has numerus advantages, but some drowbacks also exists. One of the main concern is catalyst stability and durability. The aim of this study is catalyst durability investigation and determination of the deactivation mechanisms on the case of CaO loaded onto mesoporous neutral carrier. The experiments were carried out in continuous packed bed tubular reactor (PBR) under mild reaction conditions. The CaO-based catalyst showed high activity in continuos reaction conditions during the first 30 h of operation, the FAME content was higher then 91.5%. After 30 h the catalyst activity began to decrease, so that after 36 h the FAME content was only 36%. The analysis of the morphology and the present functional groups on the surface of the catalyst before and after the reaction clearly showed a massive deposition of organic molecules from the reaction mixture on the surface of the catalyst. Since the loss of the active species by leaching was negligible, the sheltering of the catalytic active sites by such massive deposition of the organic molecule resulted in a decrease in the activity of the used CaO-based catalyst.