Hydrodeoxygenation reactions

Oxygen-containing compounds behave in a maimer analogous to sulfur compounds and their conversion follows a parallel pathway. Water produced by hydrodeoxygenation reactions can exert a mild inhibitive role to zeolitic cracking reactions, but more importantly, may play a more destructive role of zeolite modification while in service. 

The hydrodeoxygenation reaction (HDO) is carried out in the gas phase in a fixed bed reactor (400 °C, 25 bar of hydrogen), using commercial nickel and molybdenum oxides supported on alumina as catalysts. The HDO allows a quantitative transformation of dioxygenated compounds into phenol with a selectivity of 96% [24]. Main by-products are heavy condensed polycyclic aromatic hydrocarbons. 

Centeno A, David O, Vanbellinghen C, Maggi R, Delmon B. 1997. Behaviour of catalysts supported on carbon in hydrodeoxygenation reactions. In Bridgwater AV, Boocock DGB (editors). Developments in Thermochemical Biomass Conversion, Vol. 1. London Blackie Academic Professional. 

Ferrari M, Delmon B, Grange P. 2002. Influence of the impregnation order of molybdenum and cobtilt in carbon supported catalysts for hydrodeoxygenation reactions. Ctubon 40 497-411. 

Puente G, Gil A, Pis JJ, Grange P. 1999. Effects of support surface chemistry in hydrodeoxygenation reactions over CoMo/activated carbon sulfided cattilysts. Langmuir 15 58(X)-5806. 

Hydrogen consumption in hydrodeoxygenation reactions (N-mVm oil) Hydrogen consumption in hydrodemetalization reactions (scf/bbl) Hydrogen consumption in olefins saturations reactions (N-mVm oil) Hydrogen consumption in aromatics saturation reactions (scf/bbl or N-mVm oil)... 

The copper-chromium oxide has two different active sites in a reduced state. The cuprous ions associated with a hydride and two anionic vacancies are the hydrogenation (HYD) sites. The chromium ions in the same environment are the sites where occur the isomerization (I) and the hydrodeoxygenation (HDO) reactions. The use of unsaturated ethers permits to confirm and to precise the nature and the role of the active sites. With the compounds which have the oxygen atom kept away of the catalyst s surface, the HYD activity is very low and the HDO/I ratio too, whereas, in the opposite case, these values increase. With the vinylic ethers, the saturated compound is the main product because the I and the HDO reactions proceed via a concerted mechanism with a common preliminar step and an allylic rearrangement which is impossible with geminate functions. 

Figure 1. Simple reaction scheme of 4-methyl phenol hydrodeoxygenation.

Hydrogenolysis of C-N and C-0 Bonds Hydrodenitrogenation and Hydrodeoxygenation. - The mechanisms of these reactions (abbreviated hdn and... 

The HDS and HDN reactions occur during hydrotreating and hydroreforming of crude oil, and the catalyst also promotes hydrogenation of unsaturated hydrocarbons and hydrodeoxygenation. 

In recent years, the production of simple hydrocarbrnis from biomass has attracted strong interest in the renewables community, due to the fact that the products are considered drop-in substitutes for petroleum-derived alkanes, with evident applications to fuels and chemical production. HMF has received much attention in this regard as a platform for extended carbon chain products, the hydrodeoxygenation (HDO) of which gives products which are essentially diesel or aviation fuels, depending on their hydrocarbon distribution. Aldol-type condensation reactions can take place in aqueous solution between HMF (or its derivatives) and biogenic ketones... 

Friedel-Crafts alkylation of aromatics with CMF to give rise to benzyl derivatives 34a and 34b was first demonstrated in 1909 [139] and reprised by Rauchfuss and co-worker in 2013 to provide feedstock 34c for hydrodeoxygenation to diesel-range hydrocarlxMis [140]. Similar reactions have been used to produce a range of novel monomers and polymers. Thus, Szmant et al. reported as far back as 1981 the application of CMF to the synthesis of polymeric building blocks 35 and 36, among others (Fig. 1) [141]. 

Among the various compounds models, we will demonstrate the reaction mechanism of phenol hydrodeoxygenation (HDO) published by various authors (Weigold et al., 1982 Viljava et al., 2000 Senol et al., 2007). The activation procedure on the catalyst is very significant. The phenol HDO follows mechanism in parallel, according to Figure 23.9. 

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