Hydrodeoxygenation

The hydrodeoxygenation plays a minor role in the case of the conventional feeds, whereas for the feeds derived from coal, oil shale, and, particularly from the biomass, its role can be rather crucial. This process also occurs during the hydroprocessing of petroleum fractions along with hydrodesulfurization, hydrodenitrogenation. 

The bio-oil contains complex componnds of oxygen and when processed in catalytic processes, they can produce important products of high added value. Table 23.1 shows the different compounds in compositions of bio-oil and oil (petroleum). 

Note that in the conversion of biomass is obtained 50% (wt) oxygenates, as shown in this example. 

From these compounds, there is a predominance of phenols and furans, and in a smaller proportion have been carboxylic acids, ketones, aldehydes, and alcohols. Others works of the literature discussed the hydrodeoxygenation catalytic in other raw materials (Choudhary and Phillips 2011 Mercader et al., 2011). 

The main products of this process are benzene, cyclohexane, and cyclohexane. The benzene was formed by direct hydrogenolysis from phenol, while the cyclic hydrocarbons were formed by hydrogenation of phenol via the intermediate cyclohexanol and cyclohexanone. 

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HDO Hydrodeoxygenation (yields H2O) C0-M0S2/AI2O3, Ni-MoS2/ AI2O3... 

Oxygen can be present in naphthenic acids, phenols and furan (analogue structures to thiophene and pyrrole) and higher derivatives. Oxygenated compounds give rise to corrosion and product deterioration. Hydrodeoxygenation is particularly important in the upgrading of biomass. 

Oxygenate refining was limited to chemicals recovery from the Fischer-Tropsch aqueous product and acidic isomerization of the C5-C6 naphtha. The naphtha and distillate range oxygenates were removed by hydrodeoxygenation (HDO) in hydrotreaters, before further refining. 

Deoxygenation can be done by decarboxylation, cracking, hydrodeoxygenation. The conceptual stoichiometric equations of these processes are ... 

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 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. 

Steele WV, Chirico RD (1990) Thermodynamics and the hydrodeoxygenation of 2,3-benzo-furan. Cooperative agreement no. FC22-83FE60149 (NIPEP-457). IIT Research Institute, NIPEP, Bartlesville... 

Deactivation of a Sulfided NiMo/y-AJ203 during the Hydrodeoxygenation of Bio-Oils Influence of a High Water Pressure... 

The influence of a high pressure of water on the hydrodeoxygenation activity and... 

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

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