Search

In this work, the microwave-assisted reaction of 5-hydroxymethylfurfural (5-HMF) into valuable ether and acylated production formation was investigated with the help of molybdophosphoric acid encapsulated dendritic fibrous silica (KCC-1) as a catalyst. XRD, N2 adsorption-desorption, SEM, FT-IR, NH3-TPD, and TEM were used to analyze the physicochemical and structural properties of the synthesized catalysts. The microwave etherification of 5-HMF with ethanol was tested using synthesized catalysts. The effects of the reaction temperature, reaction time, catalytic amount, and microwave power were investigated. The resulting MPA-KCC-1 and IMPA-KCC-1 catalysts demonstrated excellent activity for the etherification of 5-HMF with ethanol, producing 5-(hydroxymethyl) furfural diethyl acetal (HMFDEA) and 5-(ethoxymethyl)furfural diethyl acetal (EMFDEA) products selectively. The significant advantages of the work are the selective production of EMFDEA at 82%, the catalyst can be easily removed via filtration, and the catalyst activity remains nearly intact even after five reaction cycles. [ABSTRACT FROM AUTHOR]

Highlights • Biomass torrefied via microwave heating enhanced both the quantity and quality of bio-oil. • Parameters optimization of catalytic microwave co-pyrolysis of biomass and LDPE for bio-oil. • Temperature and catalyst dosage were key factors influencing both bio-oil yield and selectivity. • The proportion of hydrocarbons was the highest (about 40%) in the bio-oils. Abstract This study aims to produce high quality bio-oil by microwave co-pyrolysis of torrefied biomass (rice straw) and low density polyethylene (LDPE) using ZSM-5 as a catalyst. A central composite experimental design was used to optimize the reaction condition by response surface methodology analysis. The effects of reaction temperatures and catalyst dosages on the product yield and chemical selectivity of bio-oil were investigated. Results suggested that bio-oil obtained from torrefied biomass contained a lower water content compared with the control.The major chemical compounds of bio-oil were hydrocarbons, ketones, phenols, esters and alcohols (∼80%).Bio-oils with high hydrocarbon content (∼40% in the bio-oil) were obtained in the development of this experiment. Quadratic models were used to predict the bio-oil yield and chemical selectivity of the bio-oil obtained during the reactions. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is an abundant renewable resource and can be efficiently converted into bio-energy by a bio-refinery. From the various techniques available for biomass thermo-chemical conversion; microwave assisted pyrolysis (MAP) seems to be the very promising. The principles of microwave technology were reviewed and the parameters for the efficient production of bio-oil using microwave technology were summarized. Microwave technology by itself cannot efficiently produce high quality bio-oil products, catalysts are used to improve the reaction conditions and selectivity for valued products during MAP. The catalysts used to optimize MAP are revised in the development of this article. The origins for bio-oils that are phenol rich or hydrocarbon rich are reviewed and their experimental results were summarized. The kinetics of MAP is discussed briefly in the development of the article. Future prospects and scientific development of MAP are also considered in the development of this article. [ABSTRACT FROM AUTHOR]

The presented study aims to improve the quality of bio-oils by catalytic upgrading of bio-oil from microwave pyrolysis of Douglas fir pellet using transition metal modified activated carbon (AC) catalyst. A central composite experimental design (CCD) was used to optimize the reaction conditions for high quality bio-oil production. The effects of reaction temperature and reaction time on product yields were investigated. GC/MS analysis indicated that the main chemical compounds (including furans, phenols, guaiacols, and ketones/ethers) of bio-oils were in the range of 80–87% of bio-oils for most of the samples. The ketones/ethers were mainly composed of 2-cyclopen-1-one; straight chain ethers were increased up to about 38% of bio-oil; and the phenols increased from 2.5% to about 10% of the bio-oils after upgrading accompanying with the decrease of guaiacols in comparison with raw biomass pyrolysis. The reaction mechanism of this process was analyzed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Catalytic microwave pyrolysis of lignin from activated carbon was investigated. [•] 45% of phenol, 78% of total phenolics, and 15.3% of hydrocarbons were achieved. [•] The heating value of lignin-derived biochars was significantly higher than lignin. [•] The thermal degradation and reaction mechanism were analyzed. [Copyright &y& Elsevier]

Abstract: Catalytic microwave pyrolysis of biomass using activated carbon (AC) was investigated to determine the effects of pyrolytic conditions on the yields of phenol and phenolics. Bio-oils with high concentrations of phenol (38.9%) and phenolics (66.9%) were obtained. These levels were higher than those obtained by pyrolysis without AC addition and were closely related to the decomposition of lignin. A high concentration of esters (42.2% in the upgraded bio-oil) was obtained in the presence of Zn powder as catalyst and formic acid/ethanol as reaction medium. Most of the esters identified by GC–MS were long chain fatty acid esters. The high content of phenols and esters obtained in this study can be used as partial replacement of petroleum fuels after separation of oxygenates or as feedstock for organic syntheses in the chemical industry after purification. [Copyright &y& Elsevier]

• Synthesis of three-dimentional Zr incorporated FDU-5 with different Si:Zr ratios. • Valorization of biomass derivative glycerol and levulinic acid to biofuel precursors. • The Zr-FDU-5 was a highly active and selective catalyst toward the esterification of glycerol and levulinic acid. • The catalyst was efficiently recycled without loss in the activity. Zirconium incorporated three-dimensional ordered mesoporous silica (FDU-5) catalysts with different Si/Zr (100, 50 and 25) ratios were synthesized using an Evaporation Induced Self Assembly (EISA) method to maximize the incorporation of zirconium sites in the silica framework. The physicochemical properties of the synthesized materials were characterized by several techniques such as XRD, N 2 sorption, diffuse reflectance UV–Vis, TEM, ammonia TPD, ICP-OES and pyridine adsorbed FT-IR. The catalytic activity was evaluated in acid-catalyzed esterification of glycerol with acetic acid. The effects of different reaction parameters were studied to optimize the maximum yields, such as reaction temperature, catalyst loading, acid/alcohol molar ratio, and reaction time. Esterification of glycerol with levulinic acid and levulinic acid with ethanol was also performed to synthesize fuel precursors. Reaction results showed that the prepared Zr-FDU-5(25) material was a very high catalytic activity, which depended mostly on the zirconium species' availability on the surfaces and framework. This zirconium containing FDU-5 material was very active in the esterification reaction and selective product formation at certain reaction conditions. The selected catalyst was recycled five times without significant loss in its activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Microwave pyrolysis of Douglas fir sawdust pellet was investigated to determine the effects of reaction temperature and time on the yields of bio-oil, syngas, and charcoal using a central composite design (CCD) and response surface analysis. The research results indicated that thermo-chemical conversion reactions can take place rapidly in large-sized biomass pellet by using microwave pyrolysis. The yields of bio-oil and syngas were increased with the reaction temperature and time. The highest yield of bio-oils was 57.8% (dry biomass basis) obtained at 471°C and 15min. GC/MS analysis indicated that the bio-oils were mainly composed of phenols, guaiacols, furans, ketones/aldehydes, and organic acids. The yield of specific chemicals such as furans and phenolic compounds were highly related to the reaction temperature. The syngas contained high value chemicals, such as carbon monoxide, methane, and short chain hydrocarbons. A third-order reaction mechanism fits well the microwave pyrolysis of Douglas fir pellet with activation energy of 33.5kJ/mol and a frequency factor of 3.03s−1. [Copyright &y& Elsevier]

Abstract: Microwave pyrolysis of distillers dried grain with solubles (DDGS) was investigated to determine the effects of pyrolytic conditions on the yields of bio-oil, syngas, and biochar. Pyrolysis process variables included reaction temperature, time, and power input. Microwave pyrolysis of DDGS was analyzed using response surface methodology to find out the effect of process variables on the biofuel (bio-oil and syngas) conversion yield and establish prediction models. Bio-oil recovery was in the range of 26.5–50.3wt.% of the biomass. Biochar yields were 23.5–62.2% depending on the pyrolysis conditions. The energy content of DDGS bio-oils was 28MJ/kg obtained at the 650°C and 8min, which was about 66.7% of the heating value of gasoline. GC/MS analysis indicated that the biooil contained a series of important and useful chemical compounds: aliphatic and aromatic hydrocarbons. At least 13% of DDGS bio-oil was the same hydrocarbon compounds found in regular unleaded gasoline. [Copyright &y& Elsevier]