anbing Ji

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.

Role of Brønsted acid in selective production of furfural in biomass pyrolysis

In this work, the role of Brønsted acid for furfural production in biomass pyrolysis on supported sulfates catalysts was investigated. The introduction of Brønsted acid was shown to improve the degradation of polysaccharides to intermediates for furfural, which did not work well when only Lewis acids were used in the process. Experimental results showed that CuSO4/HZSM-5 catalyst exhibited the best performance for furfural (28% yield), which was much higher than individual HZSM-5 (5%) and CuSO4 (6%). The optimum reaction conditions called for the mass ratio of CuSO4/HZSM-5 to be 0.4 and the catalyst/biomass mass ratio to be 0.5. The recycled catalyst exhibited low productivity (9%). Analysis of the catalysts by Py-IR revealed that the CuSO4/HZSM-5 owned a stronger Brønsted acid intensity than HZSM-5 or the recycled CuSO4/HZSM-5. Therefore, the existence of Brønsted acid is necessary to achieve a more productive degradation of biomass for furfural.

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.

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.

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.