In the series study, rice husk and corn stalk have been pyrolyzed in an auger pyrolysis reactor at various pyrolysis temperatures of 350, 400, 450, 500, 550 and 600 °C in order to investigate the effect of the pyrolysis temperature on the pyrolysis performance of the reactor and physicochemical properties of pyrolysis products (this part focus on the char and gas, the next part focus on the pyrolysis liquid). The results have shown that the pyrolysis temperature significantly affects the mass yields and properties of the pyrolysis products. The mass yields of pyrolysis liquid and char are comparable to

Two nickel-based catalysts were prepared and investigated in relation to their influence over aromatic compounds contained in tar from the pyrolysis−gasification of refuse derived fuel (RDF), using a two-stage reaction system. The results were compared with those obtained in experiments carried out using a bed of sand, both with steam and without steam. The condensed tar was analyzed for its polycyclic aromatic hydrocarbon (PAH) content using gas chromatography−mass spectrometry (GC-MS), size exclusion chromatography (SEC), and Fourier transform infrared spectroscopy (FTIR) techniques. It was found that, in the presence of Ni/α-Al 2 O 3 catalysts, some of the PAHs from three to four rings were eliminated; however, some single-ring and two-ring compounds such as styrene and indene were identified. This was also inferred from the molecular mass data (SEC). The identified PAHs consisted mainly of naphthalene, biphenyl, acenaphthylene, fluorene, and phenanthrene, but other PAHs also were identified for example: methylnaphthalenes. The influence of catalyst type on the gas composition showed that, using a 10 wt % Ni/α-Al 2 O 3 catalyst, ∼45 vol % of hydrogen was achieved, while the CH 4 and C 2 −C 4 concentrations were markedly reduced, compared with the 5 wt % Ni/α-Al 2 O 3 catalyst, which gave similar results to those obtained with the sand bed under the same conditions. The presence of oxygenated compounds in the tar samples was compared at different gasification temperatures. The results showed the presence of oxygenated compounds such as catechols and alcohols at 600 °C, these compounds were reduced as the gasification temperature increased, while the concentration of aromatic compounds increased.

Abstract:A Ni-Mg-Al-Ca catalyst was prepared by a co-precipitation method for hydrogen production from polymeric materials. The prepared catalyst was designed for both the steam cracking of hydrocarbons and for the in situ absorption of CO 2 via enhancement of the water-gas shift reaction. The influence of Ca content in the catalyst and catalyst calcination temperature in relation to the pyrolysis-gasification of a wood sawdust /polypropylene mixture was investigated.The highest hydrogen yield of 39.6 mol H 2 /g Ni with H 2 /CO ratio of 1.90 was obtained in the presence of the Ca containing catalyst of molar ratio Ni:Mg:Al:Ca = 1:1:1:4, calcined at 500 °C.In addition, thermogravimetric and morphology analyses of the reacted catalysts revealed that Ca introduction into the Ni-Mg-Al catalyst prevented the deposition of filamentous carbon on the catalyst surface. Furthermore, all metals were well dispersed in the catalyst after the pyrolysisgasification process with 20-30 nm of NiO sized particles observed after the gasification without significant aggregation.

A series of Ni/SiO 2 catalysts have been prepared and investigated for their suitability for hydrogen production and tar reduction in a two-stage pyrolysis-reforming system, using refuse derived fuel (RDF) as the raw material. Experiments were conducted at a pyrolysis temperature of 600 ºC, and a reforming temperature of 800 ºC. The product gases were analysed by gas chromatography (GC) and the condensed fraction was collected and quantified using gas chromatography-mass spectrometry (GC-MS). The effects of the catalyst preparation method, nickel content and the addition of metal promoters (Ce, Mg, Al), were investigated. Catalysts were characterised using BET surface area analysis, temperature programmed oxidation (TPO), and scanning electron microscopy (SEM). The TPO and SEM analysis of the reacted catalysts showed that amorphous type carbons tended to be deposited over the Ni/SiO 2 catalysts prepared by impregnation, while filamentous type carbons were favoured with the sol-gel prepared catalysts. The influence of catalyst promoters (Ce, Mg, Al) added to the Ni/SiO 2 catalyst prepared by the sol-gel method was found not to be significant, as the H 2 production was not increased and the tar formation was not reduced with the metaladded catalyst. The highest H 2 concentration of 57.9 vol.% and lower tar amount produced of 0.24 mg tar /g RDF ; were obtained using the 20 wt.% Ni/SiO 2 catalyst prepared by sol-gel. On the other hand a low catalytic activity for H 2 production and higher tar produced were found for the impregnated series of catalysts, which might be due to the smaller surface area, pore size and due to the formation of amorphous carbons on the catalyst surface. Alkenes and alcohol functional groups were mainly found in the analysed tar samples, with major concentrations of styrene, phenol, indene, cresols, naphthalene, fluorene, and phenanthrene.

Biomass gasification has been extensively studied in different thermochemical systems, as has the potential to produce fuel gas for chemicals, fuel and electricity applications. Circulating fluidised bed systems (CFB) are of particular interest due to the high reaction rates and thermal efficiency. The study of varying particle properties and gas velocities during the solids recirculation in a CFB system has been proved to greatly influence the overall biomass gasification process. A comparison between experimental and modelling gas-solid interactions can represent a comprehensive and analytical approach for further understanding and scaling up this reaction system. However, running several experiments is expensive and time-consuming. In this work, a reliable and accurate computational fluid dynamics (CFD) framework has been developed to evaluate the hydrodynamics performance of a CFB gasifier. The multiphase CFD model was validated using a pilot-scale CFB gasifier and silica sand. The CFD and experimental data showed good agreement for the solid recirculation tests, for example when comparing predicted and measured the spatial distribution of pressure up the gasifier's riser. It is the first time that the spatial distribution of solids around a CFB system has been numerically predicted, which can provide guidance to evaluate the hydrodynamics performance of CFB.

Ultrasound‐assisted extraction of anthocyanins and total phenolic compounds from the dried cob of purple waxy corn was investigated using response surface methodology, where the process variables were ultrasound amplitude levels (25, 50, 100%) and different solvents (pure water, water–ethanol ratio 1:1, pure ethanol), using a sample–solvent ratio of 1:20, and extraction temperature of 65 °C for 30 min. Central composite face‐centered design was used to determine optimum process conditions. The results showed that the overall optimal condition for simultaneous extraction of anthocyanins and phenolic compounds was obtained by using 50% water in water–ethanol mixed solvent as solvent and amplitude level of 50%. The optimal yields of anthocyanins and phenolic compounds were 240.161 μg cyanidin‐3‐glucoside/g dry sample and 27.662 mg gallic acid/g dry sample, respectively. The result for the antioxidant activity of the extract obtained from this optimal extraction condition to decrease the initial DPPH• concentration by 50% was approximately 4.64 mg/ml. Practical applications This article has practical application to study extraction of total anthocyanins and total phenolic compounds from dried cob of purple waxy corn using ultrasound‐assisted extraction. The response surface method using central composite face‐centered design was successfully employed to predict the effect of two independent variables on the ultrasound assisted extraction of total anthocyanins and total phenolic compounds. Moreover, the methodology and results presented in this study could be beneficial for future efforts to increase the recovery of potentially bioactive compounds from fruits, vegetables, plants and agricultural residues.

Two anhydrosugar model compounds (cellobiose and levoglucosan), and a mixture of anhydrosugars from the fast-pyrolysis of birch wood were subjected to acid hydrolysis using sulfuric acid as catalyst. The anhydrosugars mixture or bio-oil aqueous fraction was found to contain mainly levoglucosan with a concentration of 30 g L-1. Hydrolysis temperature, reaction time, and catalyst to substrate molar ratios (c/s), were varied to identify their influence for glucose production. At 120 °C, 60 minutes, and 0.9 c/s ratio; glucose yields of 98.55% and 96.56%, and substrate conversions of 100% and ~92%, were achieved when hydrolysing cellobiose and levoglucosan respectively. An increase in the temperature to 135 °C, resulted in a decrease in both glucose yield and selectivity; whereas substrate conversions around 90% were maintained for both anhydrosugars. During the hydrolysis of the bio-oil fraction, a range of conditions to achieve glucose yields above 90%, was depicted. It was found that c/s ratios between 0.17 and 0.90, and temperatures between 118 °C and 126 °C were suitable to achieve glucose yields around 100% (30 g L-1). Furthermore glucose concentrations ~117% (35 g L-1) and levoglucosan conversions above 90%, were attained at 135 °C, 20 minutes and 0.2 estimated c/s ratio.

Hydrogen production from the pyrolysis/reforming of refuse derived fuel (RDF) was investigated with a series of Ni/SiO 2 catalysts. The catalysts were prepared by homogeneous precipitation derived from a sol-gel method (HPG) and compared to Ni/SiO 2 catalysts prepared by adding a phase separation step to the HPG process (B-HPG). All the catalysts had a NiO loading of 10 wt.%, and three different calcination temperatures (500 ºC, 700 ºC and 900 ºC) were used for each method. The prepared Ni/SiO 2 catalysts were analysed to determine their surface area, and porosity characteristics; additionally scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) analyses were carried out. The results showed that the catalyst prepared by HPG and calcined at 700 ºC (HPG700), presented a relatively high surface area (~347 m 2 g -1 ), large pore diameter (12.50 nm), and also resulted in the highest catalytic activity towards H 2 production, attaining ~60 vol.% hydrogen. The lowest hydrogen concentration of about 42 vol.% was obtained using the catalysts prepared by the combined HPG-phase separation method, and calcined at 900 ºC (B-HPG900). It was also observed that at calcination temperatures higher than 700 ºC the catalytic activity for hydrogen production was diminished for both preparation methods.