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The potential of hydroquinone (HQ) clathrates to selectively separate/capture CO2 from mixtures of CO2 and H2 gas is investigated. Selective CO2 enclathration within cages of a HQ framework, from mixtures of various concentrations of the two gases, are identified using 13C nuclear magnetic resonance (NMR) and Raman spectra. Spectroscopic results indicate that CO2 molecules from the gas mixture are exclusively accommodated into the cages of HQ clathrates and that the H2 molecules are thereby concentrated in the remaining gas phase. Quantitative evidence is presented by deconvolution of NMR peaks and an elemental analyzer that CO2 molecules can be captured into the clathrate compound even at the partial CO2 fugacity of 0.38 MPa in the gas mixtures tested. Storage capacity of 53–64.4 L of CO2/kg of HQ for the HQ clathrate with full conversion makes a HQ-clathrate-based process viable for pre-combustion CO2 separation.

Abstract:The aim of this study was to investigate the optimal temperature range for waste wood and the effect torrefaction residence time had on torrefied biomass feedstock. Temperature range of 200-400 • C and residence time of 0-50 min were considered. In order to investigate the effect of temperature and residence time, torrefaction parameters, such as mass yield, energy yield, volatile matter, ash content and calorific value were calculated. The Van Krevelen diagram was also used for clarification, along with the CHO index based on molecular C, H, and O data. Torrefaction parameters, such as net/gross calorific value and CHO increased with an increase in torrefaction temperature, while a reduction in energy yield, mass yield, and volatile content were observed. Likewise, elevated ash content was observed with higher torrefaction temperature. From the Van Krevelen diagram, it was observed that at 300 • C the torrefied feedstock came in the range of lignite. With better gross calorific value and CHO index, less ash content and nominal mass loss, 300 • C was found to be the optimal torrefaction temperature for waste wood.

This study presents the effects of torrefaction on the basic characteristics of corn stalks. Corn stalks were torrefied in a horizontal tubular reactor at temperatures ranging from 150 °C to 400 °C, for torrefaction periods varying from 0 min to 50 min. The torrefied corn stalk products were characterized in terms of their elemental composition, energy yield, ash content, and volatile fraction. The gaseous products were also analyzed. Thermogravimetric analysis (TGA) of the samples was carried out in order to obtain the apparent activation energy for the torrefaction of corn stalks. The weight loss data according to the degradation temperature were analyzed using three different methods. The energy and mass yield were found to decrease with an increase in the temperature, whereas the higher heating value (HHV) increased. From this work, it was found that the compounds with oxygen were emitted at a temperature lower than that for hydrocarbon gases and the temperatures of 290-330 °C were the optimum torrefaction temperatures for corn stalks.

The separation of ethylenediamine (EDA) from aqueous solution is a challenging problem because its mixture forms an azeotrope. Pressure-swing distillation (PSD) as a method of separating azeotropic mixture were investingated. For a maximum-boiling azeotropic system, pressure change does not greatly affect the azeotropic composition of the system. However, the feasibility of using PSD was still analyzed through process simulation. Experimental vaporliquid equilibrium data of water-EDA system was studied to predict the suitability of thermodynamic model to be applied. This study performed an optimization of design parameters for each distillation column. Different combinations of operating pressures for the low-and high-pressure columns were used for each PSD simulation case. After the most efficient operating pressures were identified, two column configurations, low-high (LP+HP) and high-low (HP+ LP) pressure column configuration, were further compared. Heat integration was applied to PSD system to reduce low and high temperature utility consumption.

Thermal pre-treatment of non-lignocellulosic biomass, sewage sludge, using a lab-scale fluidized bed reactor was carried out in order to enhance its solid fuel properties. The influence of the torrefaction temperature range from 200-350 • C and 0-50 min residence time on the physical and chemical properties of the torrefied product was investigated. Properties of the torrefied product were analyzed on the basis of the degree of torrefaction, ultimate and proximate analysis, and gas analysis. An attempt was made to obtain the chemical exergy of sewage sludge. An elevated torrefaction temperature presented a beneficial impact on the degree of torrefaction and chemical exergy. Moreover, the effect of the torrefaction temperature and residence time on the elemental variation of sewage sludge exhibited an increase in the weight percentage of carbon while the H/C and O/C molar ratios deteriorated. Additionally, the product gas emitted during torrefaction was analyzed to study the pathway of hydrocarbons and oxygen containing compounds. The compounds with oxygen were emitted at higher temperatures in contrast to hydrocarbon gases. In addition, the study of various correlations for predicting the calorific value of torrefied sewage sludge was made.

The kinetic analysis method for degradation of wood in supercritical ethanol and methanol was proposed in this work. This method was applied to predict the degradation of wood in supercritical ethanol and supercritical methanol by a nonisothermal weight loss technique with heating rates of 3.1, 9.8, and 14.5°C/min for ethanol and 5.2, 11.3, 16.3°C/min for methanol. To verify the effectiveness of the kinetic analysis proposed in this work, the experimental values were compared with those of the numerical integration results using kinetic parameters obtained in this work. The kinetic analysis method proposed in this work gave reliable values of kinetic parameter for wood degradation in supercritical ethanol and supercritical methanol. To understand the effectiveness of the solvents as supercritical fluid, the calculation results of wood weight loss using the kinetic parameters obtained from this work were studied at a heating rate of 7°C/min for both supercritical ethanol (SCE) and supercritical methanol (SCM). From this work, it can be seen that SCE is better solvent than SCM for wood degradation in supercritical alcohols.