Gas phase oxidation of furfural to maleic anhydride on V 2 O 5 /γ-Al 2 O 3 catalysts: Reaction conditions to slow down the deactivation

Abstract

An alumina-supported vanadium oxide catalyst (13.9 wt. % of vanadium oxide) has been tested on the gas phase oxidation of furfural and characterised by different techniques. These studies have showed that catalyst unavoidably deactivates by deposition of maleates and resins over the surface. Full regeneration is accomplished by burning off these deposits at 773 K. The studies have also demonstrated that if the primary contact occurs at temperatures at which furfural conversion is low and then the temperature is increased in a low to high temperature mode, an intense deposition of maleates and resins takes place and the catalyst is rapidly deactivated. The increasing of the temperatures does not result in removal of deposits but accelerates the deposition. Under this protocol the yield of maleic anhydride never exceeded 30 %, irrespective of the reaction conditions (temperature and O 2 /furfural mol ratio). On the contrary if the catalyst first contacts the reaction mixture at high oxidising potential, then the rate of maleate and resins deposition is much slower and so is the deactivation rate and the catalyst can display a higher yield of MA for longer period of time. A high oxidizing potential can be accomplished at high reaction temperature (close to full conversion). Higher oxidising potential 2 at a given high temperature can be accomplished by increasing the O 2 /furfural mol ratio. Thus, for example, first contacting the catalyst at 593 K (full conversion), 1 vol. % of furfural and an O 2 /furfural mol ratio = 10, maleic anhydride yield of 68 % was initially obtained and was still greater than 50 % after 15 h on stream. When contacting at 573 with 1 vol. % furfural and 29 vol. % of O 2 , the maleic anhydride yield was initially close to 75 % and above 60 after 15 h.

Recent advances in the conversion of furfural into bio-chemicals through chemo- and bio-catalysis

“…MAnh is a key chemical intermediate employed for the production of lubricant additives, unsaturated polyester resins, pharmaceuticals, plasticizers, etc. 21,26,[37][38][39][40][41][42] At present, MAnh is industrially manufactured via the gas phase oxidation of benzene and n-butane at high temperatures. 40 Considering the increasing depletion of fossil sources and chemical sustainability, the production of MAnh using renewable biomass derivatives as the starting materials is highly promising.…”

Value-Added Bio-Chemicals Commodities from Catalytic Conversion of Biomass Derived Furan-Compounds

“…In the last years different conversion routes have been technically demonstrated to turn this petrochemical into a renewable chemical by the oxidation of different renewable platforms like 1-butanol [69], levulinic acid [70], HMF [33,[71][72][73] and FF [13,31,[74][75][76][77][78][79][80][81] using O 2 (see Table 4). Moreover, contrary to the current conventional process carried out in the gas phase, depending on the reaction conditions and the used reactant, the MAN production can be performed in the aqueous or gas phase.…”

“…Finally, oxidation of FF in the gas phase is also reported using different vanadium oxide-based catalysts (V oxide, V-Mo and V-Bi mixed oxides); however, most of the references date from the first part of the 20th century [31,89,[94][95][96]. More recently, López-Granados et al has reported some promising results [31,89] using vanadium oxide supported on alumina. Thus, at 300 • C and using 1% of FF in air (vol%) and a O 2 /FF molar ratio of 20, an initial yield well above 70% was obtained.…”

“…and has an annual consumption of more than 1600 Kt [28][29][30]. Two principal feedstocks are currently used for its industrial production, benzene and n-butane, which can be substituted by the aforementioned two platform molecules [31][32][33].…”

Common Reactions of Furfural to scalable processes of Residual Biomass

“…The best conditions of reaction were at 573 K using 1 vol.% furfural and 20 vol.% O 2 , to obtain 60% of maleic anhydride yield after 15 of reaction. Therefore, the high oxidizing potential of the reaction mixture favor the selective transformation to maleic acid and to prevent resin and maleate formation and subsequent deactivation [70].…”