RESUMO
The transformation of biomasses from agro-industrial waste can significantly impact the production of green chemicals from sustainable resources. Pectin is a biopolymer present in lignocellulosic biomass as Orange Peel Waste (OPW) and has possibilities for making platform compounds such as furfural for sustainable chemistry. In this work, we studied the transformation to furfural of OPW, pectins, and D-galacturonic acid (D-GalA), which is the main component (65 wt%) of pectin. We analyzed pectins with different degrees of esterification (45, 60 and 95 DE) in a one-pot hydrolysis reaction system and studied the differences in depolymerization and dehydration of the carbohydrates. The results show that the production of furfural decreases as the DE value increases. Specifically, low DE values favor the formation of furfural since the decarboxylation reaction is favored over deesterification. Interestingly, the furfural concentration is dependent upon the polysaccharide composition of pentoses and uronic acid. The obtained concentrations of furfural (13 and 14 mmol/L), D-xylose (6.2 and 10 mmol/L), and L-arabinose (2.5 and 2.7 mmol/L) remained the same when the galacturonic acid was fed either as a polymer or a monomer under the same reaction conditions (0.01 M SA, 90 min and 433 K). OPW is proposed as a feedstock in a biorefinery, in which on a per kg OPW dry basis, 90 g of pectin and 15 g of furfural were produced in the most favorable case. We conclude that the co-production of pectin and furfural from OPW is economically feasible.
RESUMO
Iron oxide-supported gold samples were prepared by co-precipitation from HAuCl(4) and Fe(NO(3))(3). The activities of the samples as CO oxidation catalysts were tested without thermal treatment and following treatments in flows of He and O(2) at various temperatures. It was found that the untreated samples and those treated in a flow of He at 150 °C were more active than samples that had been treated at 400 °C in either a flow of O(2) or of He. Infrared spectra recorded during CO oxidation catalysis indicate the presence of bonded CO molecules to cationic gold on all samples, whereas spectra of the least active catalysts indicate a predominant presence of Fe(2+) carbonyls, which were highly stable under the conditions of our experiments. Our results indicate that in the least active samples the Fe(2+)-bound CO blocks sites that would otherwise be available for oxygen activation.