A simple desulfurization process to achieve high efficiency, sustainability and cost-effectivity via peroxotungstate catalyst

Abstract

• Peroxotungstate presented higher desulfurization efficiency than peroxomolybdate. • The [BMIM]PF 6 was used as extraction solvent and as catalyst entrapment. • Peroxotungstate promoted high desulfurization efficiency using low amounts of oxidant, catalyst and solvent. • Complete desulfurization was achieved after 40 min using H 2 O 2 /S = 4. • Catalyst and [BMIM]PF 6 solvent were reused for consecutive cycles with high efficiency. The creation of more sustainable and high efficient desulfurization system, capable to operate under cost-effective conditions, led to the application of peroxopolyoxometalates as active oxidative catalysts. These compounds present active peroxo groups in their structure that promote easily the oxidation of sulfur compounds in the presence of low amounts of oxidant (H 2 O 2 /S = 4). The sustainability of the desulfurization of a multicomponent model diesel (2000 ppm S) was increased by the optimization of various parameters, such as nature and volume of extraction solvent, oxidant and catalyst. The Venturello peroxotungstate ((Bu 4 N) 3 PW 4 ) showed to be a catalyst able to complete desulfurize a model diesel (after only 40 min), under lower amounts of solvent, oxidant and catalyst, than the analogues peroxomolybdate ((Bu 4 N) 3 PMo 4 ) compound. Furthermore, the (Bu 4 N) 3 PW 4 /[BMIM]PF 6 system was able to be reused for six consecutive desulfurization cycles maintaining its efficiency. The oxidized sulfur compounds were removed from [BMIM]PF 6 phase in the end of each catalytic cycle. This simple procedure guarantees the cost-efficiency of the process, promoting the reuse of the catalyst and the solvent for various consecutive cycles, without the need of heterogenization techniques.