This article presents a comprehensive review of the catalytic hydrogenation of levulinic acid and alkyl levulinates into their derived biofuels and high-value chemicals, and includes the synthesis of levulinic acid and alkyl levulinates from biomass derivates.

The CO2 sorption/desorption kinetic behaviors on Li4SiO4 were analyzed. The theoretical compositions of the sorption/desorption reactions were calculated using FactSage. The sorption/desorption process on Li4SiO4 was investigated by comparing the shrinking core, double exponential, and Avrami–Erofeev models. The Avrami–Erofeev model fits the kinetic thermogravimetric experimental data well and, together with the double‐shell mechanism, clearly explains the sorption/desorption mechanism. The sorption process is limited by the rate of the formation and growth of the crystals with double‐shell structure consisting of Li2CO3 and Li2SiO3. The whole desorption process is found to be controlled by the rate of the formation and growth of the Li4SiO4 crystals. Furthermore, the influence of steam on the CO2 sorption process was analyzed. It has been observed that the presence of steam enhance the mobility of Li+ and, therefore, the rate of diffusion control stage. © 2012 American Institute of Chemical Engineers AIChE J, 59: 901–911, 2013

Intramolecular H-migration reaction of hydroperoxyalkylperoxy radicals (OQOOH) is one of the most important reaction families in the low-temperature oxidation of hydrocarbon fuels. This reaction family is first divided into classes depending upon H atom transfer from -OOH bonded carbon or non-OOH bonded carbon, and then the two classes are further divided depending upon the ring size of the transition states and the types of the carbons from which the H atom is transferred. High pressure limit rate rules and pressure-dependent rate rules for each class are derived from the rate constants of a representative set of reactions within each class using electronic structure calculations performed at the CBS-QB3 level of theory. For the intramolecular H-migration reactions of OQOOH radicals for abstraction from an -OOH substituted carbon atom (-OOH bonded case), the result shows that it is acceptable to derive the rate rules by taking the average of the rate constants from a representative set of reactions with different sizes of the substitutes. For the abstraction from a non-OOH substituted carbon atom (non-OOH bonded case), rate rules for each class are also derived and it is shown that the difference between the rate constants calculated by CBS-QB3 method and rate constants estimated from the rate rules may be large; therefore, to get more reliable results for the low-temperature combustion modeling of alkanes, it is better to assign each reaction its CBS-QB3 calculated rate constants, instead of assigning the same values for the same reaction class according to rate rules. The intramolecular H-migration reactions of OQOOH radicals (a thermally equilibrated system) are pressure-dependent, and the pressure-dependent rate constants of these reactions are calculated by using the Rice-Ramsberger-Kassel-Marcus/master-equation theory at pressures varying from 0.01 to 100 atm. The impact of molecular size on the pressure-dependent rate constants of the intramolecular H-migration reactions of OQOOH radicals has been studied, and it is shown that the pressure dependence of the rate constants of intramolecular H-migration reactions of OQOOH radicals decreases with the molecular size at low temperatures and the impact of molecular size on the pressure-dependent rate constants decreases as temperature increases. It is shown that it is acceptable to derive the pressure-dependent rate rules by taking the average of the rate constants from a representative set of reactions with different sizes of the substitutes. The barrier heights follow the Evans-Polanyi relationship for each type of intramolecular hydrogen-migration reaction studied. All calculated rate constants are fitted by a nonlinear least-squares method to the form of a modified Arrhenius rate expression at pressures varying from 0.01 to 100 atm and at the high-pressure limit. Furthermore, thermodynamic parameters for all species involved in these reactions are calculated by the composite CBS-QB3 method and are given in NASA format.

Chemical conversion of biomass to value-added products provides a sustainable alternative to the current chemical industry that is predominantly dependent on fossil fuels. N-Heterocycles, including pyrroles, pyridines, and indoles, etc., are the most abundant and important classes of heterocycles in nature and widely applied as pharmaceuticals, agrochemicals, dyes, and other functional materials. However, all starting materials for the synthesis of N-heterocycles currently are derived from crude oil through complex multistep-processes and sometimes result in environmental problems. In this study, we show that N-heterocycles can be directly produced from biomass (including cellulose, lignocelluloses, sugars, starch, and chitosan) over commercial zeolites via a thermocatalytic conversion and ammonization process (TCC-A). All desired reactions occur in one single-step reactor within seconds. The production of pyrroles, pyridines, or indoles can be simply tuned by changing the reaction conditions. Meanwhile, N-containing biochar can be obtained as a valuable coproduct. We also outline the chemistry for the conversion of biomass into heterocycle molecules by the addition of ammonia into pyrolysis reactors demonstrating how industrial chemicals could be produced from renewable biomass resources. Only minimal biomass pretreatment is required for the TCC-A approach.

In this study, renewable pyridines could be directly produced from glycerol and ammonia via a thermocatalytic conversion process with zeolites. The major factors, including catalyst, temperature, weight hourly space velocity (WHSV) of glycerol to catalyst, and the molar ratio of ammonia to glycerol, which may affect the pyridine production, were investigated systematically. The optimal conditions for producing pyridines from glycerol were achieved with HZSM-5 (Si/Al = 25) at 550°C with a WHSV of glycerol to catalyst of 1 h −1 and an ammonia to glycerol molar ratio of 12 : 1. The carbon yield of pyridines was up to 35.6%. The addition of water to the feed decreased the pyridine yield, because water competed with glycerol on the acid sites of the catalyst and therefore impacted the acidity of the catalyst. After five reaction/ regeneration cycles, a slight deactivation of the catalyst was observed. The catalysts were investigated by N 2 adsorption/desorption, XRD, XRF and NH 3 -TPD and the results indicated that the deactivation could be due to the structure changes and the acid site loss of the catalyst. The reaction pathway from glycerol to pyridines was studied and the main pathway should be that glycerol was initially dehydrated to form acrolein and some by-products such as acetaldehyde, acetol, acetone, etc., and then acrolein, a mixture of acrolein and acetaldehyde, or other by-products reacted with ammonia to form imines and finally pyridines.

In this study we demonstrate that indoles can be directly produced by thermo-catalytic conversion of bio-derived furans with ammonia over zeolite catalysts.

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Due to the irregular polymeric structure and carbon based inactive property, lignin valorization is very difficult. In this study we proposed a new route for lignin valorization by which aromatic amines can be directly produced from lignin by ex situ catalytic fast pyrolysis with ammonia over zeolite catalysts. Meanwhile, the obtained pyrolytic biochar can be activated to produce high surface area N-doped carbon for electrochemical application. Wheat straw lignin served as feed to optimize the pyrolysis conditions. MCM-41, β-zeolite, HZSM-5, HY, ZnO/HZSM-5, and ZnO/HY were screened, and ZnO/HZSM-5 (2 wt % Zn, Si/Al = 50) showed the optimal reactivity for producing aromatic amines due to the desired pore structure and acidity. Temperature, residence time, and ammonia content in the carrier gas displayed significant effects on the product distribution. The maximum yield of aromatic amines was obtained at moderate temperatures around 600 °C, 0.57 s, and 75% ammonia in the carrier gas. Under the optimized conditions, the total carbon yields of pyrolytic bio-oil and aromatic amines were 9.8% and 5.6%, respectively. The selectivity of aniline in the aromatic amines was up to 87.3%. Moreover, the pyrolysis byproduct, biochar, was further activated by KOH at 800 °C under ammonia atmosphere for producing N-doped carbon with high surface area. The pyrolytic biochar and N-doped carbon were characterized by elemental analysis, SEM, XRD, nitrogen adsorption–desorption, and XPS. Cyclic voltammetry (CV) and galvanostatic charge–discharge were employed to investigate the electrochemical performance of pyrolytic biochar and N-doped carbon. The specific capacitance of N-doped carbon reached about 128.4 F g–1.