Comprehensive characterization of cattle manure bio-oil for scale-up assessment comparing non-equivalent reactor designs

Abstract

Microscale pyrolysis reactors are used to predict the properties of pyrolysis products and/or optimize operating conditions. However, a major challenge encountered with these systems concerns reactor scale-up, since the conception of an equivalent large-scale configuration involves a complex step of mathematical analysis of the process. Furthermore, the effect of scale for different reactor configurations, considering the ways that the reactor design can influence pyrolysis, are still unknown parameters in the process. Therefore, this work evaluated the influence of scale, for different pyrolysis reactor configurations, on the composition of the liquid product (bio-oil) obtained by thermoconversion of cattle manure, using comprehensive chemical characterization by GC/MS and UHRMS, followed by statistical analysis. The gravimetric yields of the liquid fractions produced at the micro (R1) and semi-pilot (R2) scales showed a difference of ~10%, while similarity indices of ~90% were found for the volatile constituents of the bio-oils, determined by GC/MS. The ~10% disparity for the GC-analyzable bio-oil fraction was mainly associated with higher production of methoxyphenols in the R2 process. The molecular compositions determined by UHRMS showed degrees of dissimilarity < 18%, mainly reflected in higher formation of basic polar components of the O1 and O2 classes, and acids of the O4 class, in the R2 process. The results obtained in this work suggest that for a conventional pyrolysis process, the influence of scale for reactors of different configurations is less than 20%, with the products obtained showing similar compositions if the same operating conditions are used. Therefore, the challenges encountered in the scale-up phase of the system can be minimized, since changing the scale of the pyrolysis process, even using different reactors, will result in the formation of similar products.