Homogeneous vs. heterogeneous catalysts for acceptorless dehydrogenation of biomass-derived glycerol and ethanol towards circular chemistry

Abstract

The benefits of transitioning to chemical and material circularity are readily apparent. However, identifying and developing the necessary chemical transformations for platform chemical recycling is a significant challenge. Alcohols are an important industrial platform class owing to existing demand and the potential for their renewable supply through the utilization of biomass processing waste streams. Acceptorless Dehydrogenation (AD) is a critical process in the context of circularity, particularly in the transformation of alcohols. This mini-review offers an in-depth examination of both homogeneous and heterogeneous catalytic processes used in acceptorless dehydrogenation. We primarily concentrate on two sustainable feedstocks, glycerol and ethanol. Through the assessment and juxtaposition of homogenous and heterogeneous catalysts in the context of the alcoholysis of glycerol and ethanol, we aim to establish a comparison based on activity, longevity, and the green chemistry metrics associated with the catalytic processes (specifically the E-factor; energy economy coefficient, ε; and environmental energy impact factor, ξ). We established evaluation criteria using the matrics to provide a means for comparison among homogeneous and heterogeneous catalysts and help identify promising catalyst classes that can be further developed. This review seeks to shed light on the existing constraints that must be addressed to advance the development of catalysts that are more efficient, cost-effective, and resilient for AD reactions.