Roles of inorganic potassium in the evolution of heavy volatile during cellulose steam reforming.

• The evolution of heavy volatile during cellulose steam reforming was revealed. • Heavy components were formed by polymerization accompanied with deoxygenation. • Steam simultaneously accelerated cracking and polymerization of heavy components. • KCl facilitated the generation of heavy phenols below 700℃. • Molecules below 300 Da significantly increased in the presence of KCl. Biomass sources could transform into green chemicals and energy through steam reforming but heavy components of the resulting volatile, which are the precursors of undesirable coke, would also be formed. In the current study, the evolution of heavy components from cellulose is investigated. The effects of an inorganic potassium salt KCl on the heavy component evolution during steam reforming are firstly revealed in the homogeneous steam-volatile reforming process. The results suggest that heavy components were formed by polymerization reactions accompanied with dehydration and decarboxylation. Steam and alkali metal both promoted the cracking and secondary polymerization of heavy components. In the presence of steam and alkali metal, the percentage of molecules with low weight (<250 Da) and high weight (>500 Da) both improved. KCl significantly promoted the polymerization of oxygen-containing compounds, increasing the average oxygen number of the heavy components by 1.4 to 2.2 times depending on the reaction temperatures. Heavy phenols are also promoted in the presence of alkali metal below 700℃. [ABSTRACT FROM AUTHOR]