Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, 750021, Ningxia, People's Republic of China.
Institute of Coal Chemical Industry Technology, Ningxia Coal Industry Co., Ltd. of National Energy Group, Yinchuan, 750411, People's Republic of China.
Sci Rep. 2022 Mar 10;12(1):3921. doi: 10.1038/s41598-022-07766-4.
Spent methanol-to-propylene (MTP) catalysts have a large specific surface area and high porosity but are usually disposed of in landfills directly, and recycling has rarely been reported. In this study, the spent MTP catalyst was moderately dealuminized with organic acids and etched with alkali solvent to increase its specific surface area, further silanized by octyl triethoxy silane (OTS). A novel superhydrophobic adsorbent covered with -Si(CH)CH groups was obtained. The characterization of XRD, SEM, FTIR and XPS shows that the adsorbent maintains a typical ZSM-5 zeolite structure, and the -Si(CH)CH group is successfully grafted into the sample, not only on the surface but also in some pore space. Taking high chemical oxygen demand (COD) wastewater as the object, the influence of contract time, pH and temperature on COD removal was investigated. The removal process could be better depicted by the Langmuir isotherm model and the pseudo second-order dynamic model. Furthermore, the results of the thermodynamic study (∆G is - 79.35 kJ/mol, ∆S is 423.68 J/mol K, and ∆H is 46.91 kJ/mol) show that the adsorption was a spontaneous and endothermic process. These findings indicate that the modified spent MTP catalyst has potential application for the removal of COD from wastewater.
废甲醇制丙烯（MTP）催化剂具有较大的比表面积和较高的孔隙率，但通常直接被填埋处置，很少有回收利用的报道。本研究采用有机酸对废 MTP 催化剂进行适度脱铝，并用碱溶剂刻蚀以增加其比表面积，进一步用辛基三乙氧基硅烷（OTS）硅烷化。得到了一种新型的具有-Si(CH)CH 基团覆盖的超疏水吸附剂。XRD、SEM、FTIR 和 XPS 的表征表明，吸附剂保持了典型的 ZSM-5 沸石结构，-Si(CH)CH 基团成功地接枝到样品中，不仅在表面，而且在一些孔空间中。以高化学需氧量（COD）废水为对象，考察了接触时间、pH 值和温度对 COD 去除的影响。去除过程可以更好地用朗缪尔等温线模型和准二级动力学模型来描述。此外，热力学研究的结果（∆G 为-79.35 kJ/mol，∆S 为 423.68 J/mol K，∆H 为 46.91 kJ/mol）表明吸附是一个自发和吸热的过程。这些发现表明，改性废 MTP 催化剂具有从废水中去除 COD 的潜在应用。
