Impacts of residence time on transformation of reaction intermediates and coking behaviors of acetic acid during steam reforming

Abstract

Liquid hourly space velocity (LHSV) is a critical factor in steam reforming as it not only determines process capacity of reformer, but also affect the properties of the coke formed via impacting the activation of the reactants and the formation of the products. In this study, the impacts of LHSV on the properties of the coke formed in steam reforming of acetic acid over Ni/SBA-15 catalyst were investigated. The results indicated that the increasing LHSV promoted the formation of the gaseous by-products and accelerated coking, as the low residence time was not conducive for activation of steam. The coke formed at the higher LHSV was more aromatic and have more fused but defective ring structures. Furthermore, at the low steam ratio in reactants, the high LHSV could also promoted the retainment of the carbonyl functionality in the coke. These phenomena are mainly due to the higher abundance of the organic species on surface of the catalyst under the high LHSV. In addition, not only the cavity of the carbon nanotube but also other morphologies the coke such as carbon nanofiber, bamboo-like structure and string beads-like structure was closely related to the LHSV, as LHSV impacted the reaction intermediates formed and further on the precursors of the coke.