389776 Reaction Engineering: Bridging Fundamental Engineering Approaches with Biomass Pyrolysis and Transport in Zeolites
Biomass pyrolysis has been widely explored for its potential to generate a sustainable chemical source capable of producing synthetic fuels and chemicals. Lignocellulosic biomass specifically presents great promise with its carbon rich backbone and widespread prevalence. The high temperature thermal conversion of biomass to pyrolysis oil occurs on the order of milliseconds and converts the long chain biopolymers to a carbon-rich liquid crude. The kinetics of biomass pyrolysis is greatly complicated by significant heat and mass transport challenges. The complex fluid dynamics of the reactive liquid intermediate are only beginning to be understood, including the existence of vigorous bubbling and aerosol generation. Unlike traditional crude oil, the condensed bio-oil is highly oxygenated and acidic which often requires significant upgrading prior to end use. The reactive nature of the bio-oil complicates the upgrading process by presenting difficulty in heating and vaporization where the fluid properties can drastically effect the product distributions.
Additionally, the use of zeolites is widely utilized to catalytically upgrade fuels for hydrodeoxegenation, hydrogenation, and cracking. While new materials are being synthesized with transport lengthscales that are increasingly smaller, diffusional transport limitations are presenting in the small particles. The presence of these transport limitations remains a significant technical challenge. However, the use of several experimental and computational techniques is utilized to probe the mechanistic nature of these barriers, and a greater understanding is beginning to be revealed. In this work, original findings are overviewed covering biomass pyrolysis with aerosol generation mechanisms and rate-dominant diffusion limitations in hierarchical zeolites.