(533c) Soluble Sugars from Cellulose Using Polyvinyl Chloride Derived Hydrochloric Acid As Catalyst
Municipal Solid Waste (MSW) contains a large portion of organic material that has the potential to be converted into valuable fuels through thermochemical conversion. In particular, cellulosic waste-derived sugars are important platform chemicals of biofuels and chemicals. In addition to organic wastes, MSW also contains significant quantities of halogenated plastics like polyvinyl chloride (PVC) that are difficult to recycle using traditional methods. When thermally converted (e.g., pyrolysis, gasification, and incineration), PVC produces corrosive hydrochloric acid (HCl) that can react with organic waste-derived products to form organohalogens and dioxins that create various environmental and health hazards. In the current work, we co-converted cellulose and PVC in tetrahydrofuran (THF) at elevated temperatures and pressures. The reactions were carried out in miniature Swagelok reactors with reaction temperature, time and PVC concentration as the experimental variables. The liquid product was analyzed and quantified with GC/MS/FID, and the solid residue was characterized by pyrolysis using a Frontier micropyrolyzer coupled to a GC/MS/FID. The results showed that HCl released during the thermal decomposition of PVC acts as an effective catalyst in the polar aprotic solvent to promote cellulose decomposition to soluble sugars. Levoglucosan was found to be the most abundant product. The highest monomeric sugar yield was 42% of cellulose at 335 ºC and 8 minute reaction time with 2.5% cellulose weight equivalent PVC. The liquid products also contained up to 46% of soluble oligomeric sugars and small amounts of hydroxymethylfurfural and furfural. Pyrolysis of the solid residue also produced a high yield of levoglucosan (~22%, residue weight basis), indicating the residue is unconverted or partly decomposed cellulose. Chlorinated organics were nearly absent in both the liquid product and the pyrolyzates of the solid residue, suggesting the chloride content in PVC is converted to the solvent-dissolved HCl. The present study aims to explore an environmentally friendly approach to convert mixed solid wastes into value added products.