Biomass Catalysis Research Articles

Automated Generation and Optimal Selection of Biofuel-Gasoline Blends and Their Synthesis Routes

Biomass can be converted into a plethora of compounds through different chemical transformations, thus leading to a complex network of possible synthesis steps. In this work, we propose a novel strategy that simultaneously identifies (a) the most desirable biomass-derived products for an application of interest and (b) the corresponding synthesis routes. The strategy consists of i) constructing an exhaustive network of reactions consistent with an input set of chemistry rules and ii) using the network information to formulate and solve an optimization problem that yields an optimal product distribution and the sequence of reactions that synthesize them. We use this strategy to identify potential renewable oxygenates and hydrocarbons obtained from heterogeneous catalysis of biomass that can be blended with gasoline to satisfy ASTM specifications. Multiple objectives (energy loss, catalyst requirement, and absolute heat duty) are considered, and multiple alternative solutions are found in each case. We iden...

Oxidation of biomass derived 5-hydroxymethylfurfural using heterogeneous and electrochemical catalysis

The concept of biorefineries involves multiple catalytic processes to convert biomass feedstock into valuable chemical products. While conventional catalytic biomass-related processes are thermally activated, the catalytic activation of biomass conversion reactions using an electrical interfacial potential (electrocatalysis) is new and poorly explored to date. Here, we report a comparative study of biomass catalysis using thermal heterogeneous and electrocatalysis in liquid-phase. First, the oxidation of the biomass-derived model molecule 5-hydroxymethyl-2-furfural (HMF) was studied using aqueous-phase heterogeneous catalysis under mild temperature (50°C) and pressure (10bar O2) conditions. Oxidation reactions were carried out in a semi-batch reactor to test catalytic activity of Pt/C catalyst and compared with Au/TiO2, Ru/C, Rh/C and Pd/C. The important reaction parameters such as influence of pH, effect of pressure and type of catalytic metal surface were explored. HMF degradation at higher pH in the absence of metal catalyst was discussed using in situ NMR study. At lower pH (≤7), the alcoholic group of HMF oxidizes faster than aldehyde on Pt surface, whereas at higher pH (≤13), oxidation of alcoholic group appears as the rate-limiting step. At given reaction conditions, Au shows better catalytic activity than Pt, Pd, Ru and Rh at pH 13. The heterogeneously catalyzed oxidation of HMF was then compared to the corresponding electrochemical oxidation catalysis. Electrochemical catalysis offers an added advantage by providing the electrode potential and the faradaic current as two additional external control parameters. These are helpful to tune the thermodynamic driving force, activation energy and thus the reaction rate and selectivity of complex reaction processes. The electrochemical activation of water at anodic electrode potentials results in the in situ generation of reactive oxygenated surface species from the aqueous solvent and thus eliminates the use of molecular oxygen. The electrocatalytic oxidation of HMF was found very selective for the formation of 2,5-furandicarbaldehyde.

The influence of catalyst type on the composition of upgraded biomass pyrolysis oils

The composition of oils derived from the on-line, low pressure upgrading of biomass pyrolysis oils from a fluidised bed pyrolysis unit have been investigated in relation to catalyst type. Na-ZSM-5 (partially exchanged), H-ZSM-5 and Y type zeolite catalysts, and activated alumina were used. In addition, a blank run was undertaken in which the catalyst bed was replaced by a bed of stainless steel ball-bearings to determine the influence of thermal cracking. The composition of the oils before catalysis and after catalyst upgrading were analysed by liquid chromatography fractionation, followed by coupled gas chromatography/ mass spectrometry analysis of each fraction. In particular, the aromatic and oxygenated aromatic species were identified and quantified. There were only small differences in the product yields and compositions from the catalysis of biomass derived pyrolysis oils for the Na-ZSM-5 and H-ZSM-5 catalysts. All of the catalysts were effective in deoxygenating the biomass pyrolysis oils; however, there were still significant concentrations of oxygenated compounds in the upgraded oils. The ZSM-5 catalysts gave the highest yields of hydrocarbon products when compared to the Y-zeolite and activated alumina catalysts. Significant concentrations of polycyclic aromatic hydrocarbons (PAH) were formed by all the catalysts. Some of the PAH have been shown to be carcinogenic in biological studies. The formation of coke was increased for Y-zeolite and alumina compared to the Na-ZSM-5 and H-ZSM-5 catalysts.