A series of iron and chromium-based oxides were used as catalysts for the total oxidation of residual methane under realistic after-treatment conditions. This study operated with sulfur dioxide, steam and methane concentrations similar to those typically found in natural gas turbines and natural gas-powered vehicle exhausts (around 4.6 ppmV of sulfur dioxide and 10%vol of steam alongside 312 ppmV of methane balanced in air). The catalysts were synthesised using the citrate sol-gel method and characterised by BET, XRD, TPR, in situ UV–vis, in situ DRIFTS, SEM, EDX, TEM and TGA under flowing air. The performance of the catalysts was tested at atmospheric pressure and operating temperatures between 450 °C and 550 °C using three different reactant mixtures: i) 366 ppmV of methane balanced in air, ii) 347 ppmV of methane and 5.1 ppmV of sulfur dioxide balanced in air, iii) 312 ppmV of methane, 4.6 ppmV of sulfur dioxide and 10%vol steam balanced in air. This study revealed that the iron:chromium ratio has a profound impact on the performance of the catalysts. The XRD characterisation revealed that the iron and chromium-based oxides are solid solutions of hematite and eskolaite. Furthermore, the iron oxide-rich catalysts (60%mol to 80%mol iron content) contain an additional phase, which was identified as a metastable FeCr₂O₄ mixed oxide with spinel structure. In terms of catalytic activity, resistance to sulfur poisoning and sensitivity towards steam inhibition, these two catalysts were superior to pure iron oxide and comparable to pure chromium oxide. Under dry conditions, these two catalysts achieved higher methane conversion levels than pure chromium oxide, suggesting that the metastable FeCr₂O₄ spinel gives rise to improved catalytic performance. Finally, this study has proven that the sulfur resistance characteristic of chromium oxide is maintained in iron and chromium-based oxides with a chromium oxide loading as low as 20%mol, resulting in similarly effective catalysts with a lower cost, a reduced environmental impact and a considerable reduction in the health hazards associated with the exposure to chromium.

在现实的后处理条件下，一系列铁和铬基氧化物被用作残留甲烷的总氧化的催化剂。这项研究使用的二氧化硫，蒸汽和甲烷的浓度与天然气涡轮机和天然气驱动的汽车尾气中常见的浓度相似（二氧化硫为4.6 ppmV，蒸汽体积为10％，同时甲烷在空气中的平衡浓度为312 ppmV）。使用柠檬酸溶胶-凝胶法合成催化剂，并通过BET，XRD，TPR，原位UV-vis，原位表征在流动空气下的DRIFTS，SEM，EDX，TEM和TGA。使用三种不同的反应混合物在大气压力和450°C至550°C的工作温度下测试了催化剂的性能：i）366 ppmV的甲烷在空气中平衡； ii）347 ppmV的甲烷和5.1 ppmV的二氧化硫平衡iii）312 ppmV的甲烷，4.6 ppmV的二氧化硫和10％vol的蒸汽在空气中平衡。这项研究表明，铁与铬的比例对催化剂的性能有深远的影响。XRD表征表明，铁和铬基氧化物是赤铁矿和依斯科莱特的固溶体。此外，富铁氧化物催化剂（铁含量为60％mol至80％mol）包含附加相，该相被确定为亚稳FeCr ₂ O _4。尖晶石结构的混合氧化物。在催化活性，抗硫中毒性和对蒸汽抑制的敏感性方面，这两种催化剂均优于纯氧化铁，且与纯氧化铬相当。在干燥条件下，这两种催化剂的甲烷转化率均高于纯氧化铬，表明亚稳的FeCr ₂ O ₄尖晶石提高了催化性能。最后，这项研究证明，在铁和铬基氧化物中，三氧化二铬的抗硫特性得以保持，而三氧化二铬的负载量低至20％mol，从而以较低的成本，降低的环境影响和更低的成本获得了同样有效的催化剂。显着降低了铬暴露对健康的危害。