Modified Mo/V/W‐Mixed Oxides for Catalytic Tar Removal from Biosyngas via Oxidation

Abstract

In view of the growing energy demand and the current climate problems, renewable energy sources are becoming increasingly popular. The so‐called biosyngas obtained from the gasification of dry biomass can be used to synthesize fuels and basic chemicals. Besides gaseous by‐products and salts, this gas contains tar which needs to be removed before downstream processing. Catalysts like Mo/V/W‐oxides were found to be inert towards the oxidation of CO and H2 but are able to activate the tar model compound naphthalene highly selective. Unfortunately, besides the total oxidation, the partial oxidation to the undesired intermediates phthalic acid anhydride and maleic acid anhydride takes place. Modification of the catalyst with bases leads to synergetic effects on the catalyst surface, the total oxidation is promoted, and the formation of intermediates decreases.

Catalytic Tar Removal from Bio‐Syngas via Oxidation on Metal Oxide Catalysts

“…This temperature results from the experimental knowledge that at lower temperature no conversion is achieved. Higher temperature leads to irreversible catalyst deactivation due to sinter processes, as confirmed in previous works 18, 32. In Fig.…”

“…2, the tar model components are converted largely in MAA. To prevent problems with MAA in further downstream processes, the formation of MAA can be reduced by basic modifications of the catalyst 32. Therefore, with regard to the generally accepted character of these tar model substances, it can be concluded that benzene is the less reactive compound among the investigated aromatic tar representatives.…”

“…The exact identification of every component is made according to the specific mass‐to‐charge ratio. Prior to the actual measurement, an extensive calibration with each component was carried out as described in previous works 32. The calibration itself is based on a complex matrix involving the dependencies between the ion currents and the gas concentrations as well as the fact that some components have fragment peaks at the same mass.…”

“…The spray‐dried catalyst with the general formula Mo 8 V 2 W 1 O x was prepared according to the preparation strategy developed by Kunert et al via spray‐drying of an ammonia precursor solution. Details on the preparations and the characterization of the catalyst were presented in previous works 32–34. A general scheme of the synthesis route of spray‐dried Mo/V/W‐mixed oxides is given in Fig.…”

Experimental Study on Catalytic Biomass Gasification in a Bubbling Fluidized Bed

“…At present, various methods have been proposed for tar conversion, the most important of which is using a catalyst. Up to now, many researchers have investigated the ability of catalysts in tar removal, hydrogen production, and char conversion by different methods of preparation , . These catalysts include natural ones such as dolomite and olivine as well as Ni‐based catalysts.…”