Recovery and valorization of natural resources from waste materials are crucial for promoting sustainable development. In light of this, the present study explores the transesterification of waste culinary oil into biodiesel production using a silica-supported solid super-acid catalyst (SO/TiO–SiO) prepared with recovered TiO from spent SCR. The synthesized materials were characterized through XRD, SEM-DES, XPS, FT-IR, NH-TPD, and N-BET analysis. Notably, the crystal structure of recovered TiO was not destroyed during the whole process. N-BET analysis showed that the silica-supported catalyst significantly increased the specific surface area from 47.89 to 101.16 g/m. The presence of superacid sites (Brønsted and Lewis acid sites) on the surface of the catalyst was confirmed by NH-TPD and FT-IR analysis. The silica-supported catalyst (SO/TiO–SiO) exhibited high catalytic activity for free fatty acid (FFA) about a conversion rate of 90.7 % under optimal reaction conditions: a reaction time of 4 h, at 180 °C with a 5 wt% catalyst loading, and a methanol-to-oil molar ratio of 12:1. The biodiesel production was confirmed by using FT-IR and HNMR techniques. Furthermore, the catalytic performance of the prepared catalyst was compared with other catalysts prepared from pure TiO reported in the literature. This approach showed a potential for sustainable biodiesel production by using low-cost solid acid catalyst synthesized from recovered materials.

中文翻译：

---

用废 SCR 回收的 TiO2 制备的 S2O82−/TiO2-SiO2 固体超强酸催化剂催化废弃食用油生产生物柴油

从废料中回收和增值自然资源对于促进可持续发展至关重要。有鉴于此，本研究探索了使用从废 SCR 回收的 TiO2 制备的二氧化硅负载固体超酸催化剂 (SO/TiO-SiO)，将废弃食用油酯交换成生物柴油生产。通过 XRD、SEM-DES、XPS、FT-IR、NH-TPD 和 N-BET 分析对合成材料进行了表征。值得注意的是，回收的二氧化钛的晶体结构在整个过程中没有被破坏。 N-BET分析表明二氧化硅负载的催化剂的比表面积从47.89 g/m显着增加到101.16 g/m。通过 NH-TPD 和 FT-IR 分析证实了催化剂表面存在超酸位点（Brønsted 和 Lewis 酸位点）。二氧化硅负载的催化剂（SO/TiO-SiO）对游离脂肪酸（FFA）表现出高催化活性，在最佳反应条件下（反应时间为 4 小时，180 °C，5 wt%），转化率约为 90.7%。 %催化剂负载量，甲醇与油的摩尔比为12:1。通过使用 FT-IR 和 HNMR 技术证实了生物柴油的生产。此外，将所制备的催化剂的催化性能与文献报道的其他由纯TiO制备的催化剂进行了比较。这种方法显示了利用回收材料合成的低成本固体酸催化剂可持续生产生物柴油的潜力。