Effect Of Heterogeneous Catalysts Research Articles

Liquid phase pyrolysis of wheat straw and poplar in hexadecane solvent

There is a need for replacement of fuel, especially transportation fuel, obtained from fossil resources by bio-based alternative. The thermochemical conversion is a feasible method to degrade and partially deoxygenate the natural resource lignocellulose to get bio-oils as fuel precursors. The present paper describes the liquid phase pyrolysis of wheat straw and poplar under inert atmosphere in n-hexadecane solvent. An autoclave batch reactor system was used. The influence of reaction temperature, residence time, solvent/biomass ratio and the effect of solid acid and base catalysts on the product distribution and yields were investigated. The reaction products were analyzed by means of CHNO elemental analysis, Solid Phase Micro Extraction-Gas Chromatograpy-Mass Spectroscopy (SPME-GC–MS), 1H and 13C-Nuclear Magnetic Resonance (NMR) spectroscopies. About 40–49 wt% of lignocellulosic carbon was successfully transferred to hexadecane. The best carbon yields were achieved at 350 °C. The main extracted products were alkyl and alkoxy derivatives of phenol and furan derivatives. By comparing seven parallel experiments in presence and absence of the catalysts no or only negligible catalytic effect was observed. The effect of heterogeneous catalysts was manifested only in splitting the primarily extracted macromolecules. The carbon/oxygen mass balances suggest that the extracted compounds have relatively high residual oxygen content.

Studies on the effect of heterogeneous catalysts on the hydrothermal liquefaction of sugarcane bagasse to low-oxygen-containing bio-oil

ABSTRACTDevelopment of suitable catalysts having deep deoxygenation activity is the key for the hydrothermal liquefaction (HTL) of biomass to auto fuels directly. In this study 12 catalysts, namely Fe-MCM-41, Co-MCM-41, Mo-MCM-41, Ti-MCM-41, and oxides of Fe, Co, Mo, Ti, Fe-Mo, Fe-Co, Co-Mo and Ti-Zr, were synthesised, and characterised by X-Ray Diffraction (XRD), textural analysis, Fourier Transform Infra Red (FTIR) and Scanning Electron Microscope (SEM). They were evaluated for HTL of sugarcane bagasse to bio-oil in the presence of hydrogen and carbon monoxide. For non-catalytic HTL, oil obtained in the presence of hydrogen contained less oxygen, whereas for catalytic HTL oil obtained in the presence of carbon monoxide contained less oxygen. Among the catalysts studied, iron-cobalt oxide was found to be the most selective as it gave the highest oil yield of 57.6 weight% containing the least oxygen of 10.8 weight% in the presence of CO. Co-MCM-41 and cobalt oxide yielded bio-oil with the least oxygen among the metal-substituted MCM-41 and metal oxides studied, indicating that cobalt may be the most active catalytic species for strong deoxygenation activity. Metal-substituted MCM-41 yielded oil with less oxygen compared to its simple metal oxides except Ti, which may be due to very high surface area owing to its mesoporous structure.

Preparing biodiesel fuel in supercritical fluid conditions with heterogeneous catalysts

Noncatalytic and catalytic transesterification of rape oil were studied in an ethanol medium under supercritical fluid conditions, ultrasonic effect, temperature range from 623 to 653 K, 30 MPa, and with 12: 1 and 18: 1 alcohol to oil mole ratios. An effect of heterogeneous catalysts on the reaction rate was defined. Correlation dependence between the amount of fatty acid ethyl esters in biodiesel fuel and kinematical viscosity of the reaction product was determined.

The Effect of Heterogeneous Catalysts on Hydrothermal Liquefaction of Corn Stalk under CO Atmosphere

Hydrothermal liquefaction of corn stalk under CO atmosphere with three commercial heterogeneous catalysts was performed in a high pressure autoclave. The structure and reducibility of the catalysts were studied by X-ray diffraction and differential thermal gravity under H2 atmosphere. The results indicated that the catalysts greatly increased the conversion of cornstalk yield and heating value of liquid product. The activity order of the catalysts is as follows: JT203 > JT201 > JB-1, which is consistent with the high surface area and low reduction temperature of JT203. The catalysts might favor a hydrothermal liquefaction process through the active H produced by water-gas shift reaction.

Solvent-free ring opening reaction of epoxides using quaternary ammonium salts as catalyst

Ring opening reaction of 1,2-epoxydodecane to the corresponding diacetate diester is described. Quaternary ammonium salts were found to be excellent catalysts for the acetylation reaction of the epoxide with acetic anhydride, where its activity was compared to different chloride salts. While in the presence of chloride salts no reactions were observed without activation, excellent yields (up to 100%) were achieved in the presence of quaternary ammonium salts. The effect of heterogeneous catalysts was compared to homogeneous ones.