Fengwen Yu

Quantification of glucose, xylose, arabinose, furfural, and HMF in corncob hydrolysate by HPLC-PDA-ELSD.

Lignocellulose and other carbohydrates are being studied extensively as potential renewable carbon sources for liquid biofuels and other valuable chemicals. In the present study, a simple, sensitive, selective, and reliable HPLC method using a photodiode array (PDA) detector and an evaporative light scattering detector (ELSD) was developed for the simultaneous determination of important sugars (D(+)-cellobiose, glucose, xylose, and arabinose), furfural and 5-hydroxymethylfurfural (5-HMF) in lignocellulose hydrolysate. The analysis was carried out on an Aminex HPX-87H column (250 mm × 4.6 mm, 5 μm particle size). Ultra-pure water with 0.00035 M H(2)SO(4) was used as the mobile phase with a flow rate of 0.6 mL/min. The temperature of the ELSD drift tube was kept at 50 °C, the carrier gas pressure was 350 kPa, and the gain was set at 7. Furfural and 5-HMF were quantified on a PDA detector at 275 nm and 284 nm, respectively. The sugar concentrations were determined by ELSD. This method was validated for accuracy and precision. The regression equation revealed a good linear relationship (r(2) = 0.9986 ± 0.0012) within the test ranges. The method showed good reproducibility for the quantification of six analytes in corncob hydrolysate, with intra- and inter-day variations less than 1.12%. This method is also convenient because it allows the rapid analysis of the primary products of biomass hydrolysis and carbohydrate degradation.

Study on the Pyrolysis of Cellulose for Bio-Oil with Mesoporous Molecular Sieve Catalysts

Mesoporous materials possess a hexagonal array of uniform mesopores, high surface areas, and moderate acidity. They are one of the important catalysts in the field of catalytic pyrolysis. In this paper, mesoporous materials of Al-MCM-41, La-Al-MCM-41, and Ce-Al-MCM-41 were synthesized, characterized, and tested as catalysts in the cellulose catalytic pyrolysis process using a fixed bed pyrolysis reactor. The results showed that mesoporous materials exhibited a strong influence on the pyrolytic behavior of cellulose. The presence of these mesoporous molecular sieve catalysts could vary the yield of products, which was that they could decrease the yield of liquid and char and increase the yield of gas product, and could promote high-carbon chain compounds to break into low-carbon chain compounds. Mesoporous molecular sieve catalysts were benefit to the reaction of dehydrogenation and deoxidation and the breakdown of carbon chain. Further, La-Al-MCM-41 and Ce-Al-MCM-41 catalysts can produce more toluene and 2-methoxy-phenol, as compared to the non-catalytic runs.

Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME)

Undecylenic acid methyl ester (UAME) was continuously produced from methyl ricinoleate using a microwave-assisted pyrolysis system with atomization feeding. The UAME yield of 77 wt.% was obtained at 500°C using SiC as the microwave absorbent and heating medium. The methyl ricinoleate conversion and UAME yield from microwave-assisted pyrolysis process were higher than those from conventional pyrolysis. The effect of temperature on the pyrolysis process was also investigated. The methyl ricinoleate conversion increased but the cracking liquid yield decreased when the temperature increased from 460°C to 560°C. The maximum UAME yield was obtained at the temperature of 500°C.

Thermogravimetric analysis and kinetic modelling of rice-straw pyrolysis in molten salt of alkali carbonates

The demand for sustainable development has led to a growing interest in biomass energy. Molten salts, such as alkali metallic salts, have been applied in biomass pyrolysis because of their good thermal stability, low vapour pressure, large heat capacity, large thermal conductivity, high solubility, low viscosity, and chemical stability. Using thermogravimetric analysis, this work studied the influence of sodium and potassium carbonates as additives for pyrolysis. Rice straws were mixed at different ratios with two alkali carbonates (Na2CO3, K2CO3, and their mixture, Na2CO3-K2CO3). The weight of rice straw decreased at around 200 and 380 oC in the presence of carbonates. Temperatures of initial release of volatiles decreased with the increase of mass of salt. The shoulder of the differential thermogravimetric curves appeared earlier under the catalysis by carbonates. The char yield of rice straw with added eutectic molten salt was nearly the minimum compared with that obtained with other salts. Based on this experiment, two reaction models for biomass pyrolysis were proposed. The models can describe the pyrolysis process satisfactorily over the whole temperature range. The kinetic parameters in the different reaction models were calculated by fitting single experiments and by multivariate regression. The results illustrate that the salts can decrease the activation energy and alter the paths of rice straw pyrolysis, and the catalytic activity of eutectic salts is higher than those of the individual salts.

Removal of Aromatic Compounds from Wastewater by Biodiesel

Wastewater from chemical plant, refinery and pharmaceutical factory contains many kinds of aromatic compounds. Wastewater including aromatic compounds is hazardous and difficult to be biodegraded. This study concerned the method of extracting aromatic compounds from the wastewater using biodiesel as extracting solvent. Biodiesel as solvent has some special characteristics: its solubility in water is smaller, its flash point is higher, it is nontoxic, and it is biodegradable. In this work, the solute removal rate, COD removal rate and solvent recovery were studied. In addition, the multistage countercurrent extraction experiments were carried out. The results showed that the multistage extraction rates of aniline, nitrobenzene and phenol were greater than 98.67%. The recovery performance of biodiesel was better. Biodiesel is a better extracting solvent for the wastewater containing aromatic compounds.

Conversion of sawdust to bio-fuels by pyrolysis within molten sodium hydroxide

Sawdust, a renewable by-product of furniture manufacturing industry, is an energy source that can be utilized to meet the increasing demands for energy. Pyrolysis of sawdust was performed in a self-designed reactor under the conditions of nitrogen atmosphere, the effect of feeding rate, flow rate of sweeping gas, sawdust type, and inorganic salts additive on the pyrolysis product yields from sawdust have been investigated. The results shows that the char yield increased gradually with the increasing of feeding rate, the maximum yield of liquid and gaseous attained at the feeding rate of 1.36g/min; the liquid yield decreased gradually with the increasing of sweeping gas flow rate, and the maximum of gaseous attained at the flow rate of 100L/h; different kinds of sawdust can be used to produce different pyrolysis products, and ZnCl2 can retrain the formation of liquid and char obviously, the effect on formation of gaseous was slight.

Influence of molten salts on pyrolysis characteristics of rice straw

In order to investigate the effects of molten salts on pyrolysis characteristics of rice straw, the pyrolysis behaviors of rice straw had been investigated with thermogravimtirc analysis by changing cations (Na+, K+) and anions (Cl-, CO32- and SO42-) of the molten salts, respectively. The results indicated that the pyrolysis of rice straw was occurred in the range of 200°C and 400°C. With the increase of heating rate, hysteresis was existed during the pyrolysis process, and the maximum weight loss rate increased. The pyrolysis happened at a lower temperature range and the volatile matter vapored easily under the role of CO32-, and SO42- had advantages of fixing charcoal under the same cation conditions. Compared with Na+, it was easier for K+ to generate charcoal under the same anion conditions. Integration method Ozawa was used in kinetic analysis on the samples processed by deducting the added salts, the results showed that the activation energy of rice straw under the role of NaCl, Na2SO4 and KCl decreased compared with that of the sample without additives, while the activation energy processed by Na2CO3 increased. This research can provide a certain reference for the exploitation and utilization of agricultural residues.

Study on separation the molten mixture of NaOH-Na 2 CO 3 by molten crystallization

Hydrogen production from biomass pyrolysis with molten NaOH had achieved high yield of hydrogen, but the molten mixture of Na<inf>2</inf>CO<inf>3</inf> and NaOH was obtained during the process of hydrogen production, since Na<inf>2</inf>CO<inf>3</inf> can be acted as a product and NaOH is recycled, Na<inf>2</inf>CO<inf>3</inf> and NaOH need to be separated. In this paper, the separation of molten mixture of NaOH and Na<inf>2</inf>CO<inf>3</inf> was investigated through molten crystallization. The influences of thermostatic time, depart temperature, teperature controlling way and molar content on the separation results were studyed. The results showed that the suitable thermostatic time was 30 minutes, and temperature directly dropping to desirable temperature was in favor of improving the percentage of NaOH The suitable separation temperature was impacted by the content of Na<inf>2</inf>CO<inf>3</inf>. The quality was kept constant when the molar content of Na<inf>2</inf>CO<inf>3</inf> is 25%, and the appropriate separation temperature is 370°C, which is higher 80°C than that of the molar content of 10% Na<inf>2</inf>CO<inf>3</inf>. This article provides some references for separating the residue which is attained in the process of hydrogen production by pyrolysis of biomass in molten NaOH.

Characteristics of copyrolysis polyethylene with carbon dioxide in a horizontal DC plasma jet reactor

Characteristics of copyrolysis polyethylene (PE) with greenhouse gas carbon dioxide (CO2) was investigated in a horizontal DC plasma jet reactor, for the aim to adjust the H2/CO molar ratio in the gaseous products in a wide range to further synthesize liquid fuel. For comparison, pyrolysis PE alone as well as pyrolysis CO2 alone was also studied in light of CO yield. Results showed that: in case of plasma pyrolysis PE alone, product streams included combustible gas and solid carbon, and the main components of the gaseous products consisted of a large amount of H2 achieved at 21.3 vol % and a small amount of low molecular hydrocarbon, CO was not determined in the gaseous products thanks to PE being hydrocarbon polymer. In terms of H2 yield performance, the horizontal plasma jet reactor under development was superior to the downward mode. In case of plasma pryolysis CO2 alone, just a small amount of CO obtained from the decomposing reaction of CO2, and the CO concentration in the gaseous products was less than 5%. In case of plasma copyrolysis PE with CO2, a wide range of H2/CO molar ratio in the gaseous products can be obtained with varying the inlet CO2 concentration, and the product of CO obtained mainly from the gasified reaction of carbon with CO2, in which carbon generated from plasma pyrolysis PE. In this paper, the H2/CO molar ratio was adjustable in the range of 1 to 12 from plasma copyrolysis PE with CO2. Thus, a significant synergy effect can be observed from copyrolysis PE with CO2 in terms of the CO yields.