Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción, Chile; Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco, Chile.
Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción, Chile.
J Hazard Mater. 2014 Jun 15;274:212-20. doi: 10.1016/j.jhazmat.2014.04.006. Epub 2014 Apr 13.
In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.
在这项研究中，考察了沸石化学表面特性对甲苯饱和沸石样品氧化再生的影响。采用盐酸酸处理和硫酸铵离子交换对智利天然沸石（53%斜发沸石、40%丝光沸石和 7%石英）进行了化学改性。在 623 和 823K 下进行了热预处理，生成了具有不同化学表面特性的六种沸石样品。天然沸石的化学改性随后进行热脱气，使得可以区分酸性表面位在废沸石再生中的作用。铵交换处理后在 623K 下进行热处理，导致沸石表面的 Brønsted 酸位增加，从而提高了对甲苯的吸附能力。高臭氧消耗可能与高含量的路易斯酸位有关，因为这些酸位可以将臭氧分解成原子活性氧物种。然后，表面氧化反应可以在 Brønsted 酸位和表面原子氧物种之间进行，在臭氧再生氧化后减少吸附的甲苯量。实验结果表明，吸附氧化副产物的存在对沸石吸附能力的恢复有负面影响。
