Kinetic studies on the liquid-phase catalytic oxidation of 4-methyl guaiacol to vanillin

Sulfur recycle in biogas production: Novel Higee desulfurization process using natural amino acid salts

In this work, a desulfurization method using natural amino acid salts (AAS), which can be green prepared by biological fermentation, is proposed to remove H₂S from raw biogas. Biogas purification and fertilizer production can be simultaneously achieved to close sulfur recycle. The reaction kinetic characteristics of H₂S absorption with three kinds of AAS, including potassium β-alaninate (PA), potassium sarcosinate (PS) and potassium l-prolinate (PP) are first studied. Kinetic parameters including orders of reaction, rate constants, pre-exponential factors and activation energies are given. AAS absorbent exhibits good potential for biogas desulfurization. Higee (high gravity) technology is utilized to intensify H₂S removal. The effects of operating conditions on H₂S removal efficiency are investigated and PP shows the best desulfurization performance. The phytotoxicity of AAS and amino acid salt sulfide (AASS) is assessed by the germination index of mungbean seeds. PP and its salt sulfide (PPS) show relatively low phytotoxicity and their allowable agricultural feeding concentrations are below 0.08 M and 0.04 M, respectively. The desulfurization method demonstrates a green route for biogas purification to achieve sulfur recycle.

Comparison of linear and nonlinear function to describe and predict componential evolution of biomass pyrolysis vapors during condensation in a tubular indirect heat exchanger

A novel experimental method based on the combination of bio-oil composition inversion and function fitting was purposed and verified for describing the componential evolution curves during the liquefaction of biomass pyrolysis vapors. The evolution curves of representative condensable components were fitted by linear and Slogistic function in the short, middle and long three condensing fields. Linear function exhibited a significant effectiveness for the description and prediction of low-boiling water and furfural and the relative deviations were no more than 5% between actual values in long condenser and predictive values from the elongation of curves in short and middle condensers. For high-boiling phenolic compounds, linear function failed to fit their evolutions in long condenser but Slogistic fitting remained effective despite the relative deviation increasing to about 10%. This investigation provided a unique and effective prediction method for the vapor evolution in industrial shell and tube heat exchanger according to laboratory-scale experiment.

Experimental study on the composition evolution and selective separation of biomass pyrolysis vapors in the four-staged indirect heat exchangers

This study was devoted to proposing an effective experimental method based on bio-oil composition inversion for understanding biomass pyrolysis vapor evolution in four-staged condensers. The effective length of each condenser was 200 mm. The evolution curves and heat maps of condensable vapors in the whole multi-staged condensing field were provided by Logistics model fitting. With changing condition from "365-345-325-305" to "345-325-305-285", the condensing efficiency of the first condenser increased by 100% but that of the third condenser decreased by 80%. Under condition "365-345-325-305", the largest recovery rate of water was observed at 400 mm away from multi-staged condensing field entrance while that of eugenol was observed at 50 mm away from the entrance, which explained that water was primarily recovered by the second and third condensers whereas eugenol was recovered by the first condenser, and verified the remarkable effect of fractional condensation on the separation of water and high-boiling phenols.