Chemical Looping Selective Oxidation of H₂S using V₂O₅ Impregnated over Different Supports as Oxygen Carriers

Abstract

Chemical looping concept is proposed to improve the efficiency of selective oxidation of H 2 S into elemental sulfur. V 2 O 5 as an active oxygen carrier, is impregnated on different supports and exposed cyclically to reductant (H 2 S) and to oxidant (O 2 ). Among all, TiO 2 and SiO 2 proved as better supports for V 2 O 5 as they provided more formation of elemental sulfur than undesired SO 2 in the reductant step. Results indicate that the support can either directly react and provide oxygen to the process like for CeO 2 or indirectly affect the properties of the active phase, leading either into the improvement, as for TiO 2 and SiO 2 , or worsening, as in case of Al 2 O 3 and ZrO 2 . Oxygen carriers with partially reduced species, i. e., the combination of V 5 + and V 4 + , show better performances than carriers containing mostly highly oxidized V 5 + species. Interaction between the active phase and support plays a vital role for the controls of the formation of these partially reduced species.[a] T.

Intensification of Chemical Looping Processes by Catalyst Assistance and Combination

“…Transfer of surface reaction intermediates by chemical looping (carbon, -OH, S, etc.) between distinct reactions [23,24]. Materials in these chemical looping processes can carry reaction intermediates, which are different from oxygen or CO2 (Figure 1c).…”

“…Considering that it can have various applications, starting from one common basic concept, chemical looping can be considered a true technology platform. Compared to a traditional catalytic process, the chemical looping concept allows to: (i) minimize exergy loss [8,25,26], (ii) intensify the targeted process by combining reaction and separation in a single step [27], (iii) apply H2O/CO2 as an oxidant (steam/dry reforming), which enables to produce pure H2 and CO without the need for downstream separation [8,28,29], (iv) feed lower grade or less pure feedstocks, (v) use cheap materials (CaO, FeOx) [13,30] and (vi) use fuel without the need for upstream desulfurization [23,31]. A quite notable feature is its ability to provide product separation in situ.…”

Carbon-doped boron nitride nanosheets as an efficient metal-free catalyst for the selective oxidation of H2S

“…Among other approaches, the selective oxidation of H 2 S is attractive due to its low capital cost and environmental friendliness. 5,6 The metal oxide-based catalysts (V 2 O 5 , Fe 2 O 3 , TiO 2 , ZrO 2 and many others) are the most widely adopted catalysts in the continuous process of selective oxidation of H 2 S. [7][8][9] However, this series of catalysts cannot meet the demand of high sulfur selectivity and durable stability. Moreover, the formation of metal-S bonds, due to the large overlap between sulfur p and metal d orbitals, could be induced, leading to the deactivation of the catalysts.…”