Chemical Looping with Oxygen Uncoupling of the Lignocellulosic Biomass Main Model Compound: Product Distribution and Kinetic Analysis on Lignin

Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing surface chemical kinetics. Five carbonaceous substrate-deposited Ru were synthesised and tested for the HDO of monomer moiety eugenol. Their annealing temperatures differed, specifically between 300 and 750 °C, while one was not subjected to calcination. Experiments revealed the substantial influence of annealing temperature on the product distribution. Namely, fresh nonannealed nanocomposites were not active for hydrogenolysis. By further pretreatment increase, hydrogenation and, exclusively, the deoxygenation of saturated cyclic species, were enhanced, these being more promoted considering rates and yields than commercial carbon-supported ruthenium. Over 80 mol% of 4-propyl-cylohexanol and propyl-cyclohexane could be formed over the samples, treated at 500 and 600 °C, for 100 and 125 min, respectively, under 275 °C and 5 MPa of reactor hydrogen pressure. Interestingly, a notable 4-propyl-phenol amount was produced upon 750 °C pretreating. The intrinsic microkinetic model, developed previously, was applied to determine relevant turnover parameters. Calculated modelling results indicated a 47- and 10-fold greater demethoxylation and dehydroxylation mechanism ability upon the reheatingpreheating at 600 °C in comparison to industrial (heterogeneous) Ru/C.

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Halogenation of Butyl Rubber—A Model Compound Approach

Rubber Chemistry and Technology ◽

10.5254/1.3536007 ◽

1984 ◽

Vol 57 (2) ◽

pp. 275-283 ◽

Cited By ~ 32

Author(s):

R. Vukov

Keyword(s):

Model Compound ◽

Product Distribution ◽

Butyl Rubber ◽

Methyl Groups ◽

Reaction Site ◽

Model Compounds ◽

Reaction Conditions ◽

Basic Study ◽

Rubber Model ◽

Trisubstituted Alkenes

Abstract The study of the halogenation behavior of butyl rubber model compounds has brought about a better understanding of the behavior of these systems. It has been established that the presence of methyl groups, in a position B to the reaction site in the butyl rubber model compound, profoundly influences the course of halogenation. Due to the steric hindrance imposed by these groups, both the products of chlorination and bromination deviate from patterns typical of other trisubstituted alkenes. In the case of chlorination, this deviation is demonstrated by the absence of addition products of chlorine across the double bond. In the case of bromination reactions, the change in product distribution is even more dramatic. Thus, substitution products normally not observed in bromination reactions of other trisubstituted alkenes become predominant products found in yields of between 70–90% depending on the precise reaction conditions. The behavior of the butyl model compound appears to be entirely consistent with the behavior of butyl rubber itself; the model compound approach is therefore a valuable tool for use in the basic study of this type of system.

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