ZEOLITIC SUPPORT OBTAINED FROM VOLCANIC ASHES. CATALYTIC EVALUATION IN THE CLEAN OXIDATION OF DIPHENYLSULFIDE

M. GONZALEZ; D. MONZÓN,; C. RIVERA; M. MUÑOZ; ANDREA M. PEREYRA; E. BASALDELLA

Cancún

Congreso; XXIX International Materials Research Congress; 2021

Sociedad Mexicana de Materiales

Zeolites are crystalline structures used in ion exchange, gas separation and catalysis. These materials can be synthesized a variety of aluminosiliceous raw materials, including clay minerals and industrial wastes. Additionally, volcanic ashes are constituted by a set of inorganic compounds such as amorphous silicates or aluminosilicates and some crystalline phases (particularly plagioclase). These materials also could be successfully transformed in different zeolites by an adequate selection of the operating conditions for their hydrothermal transformation. In this work, zeolitic materials were obtained volcanic ash Bariloche (Southern Argentina). The natural ash was sieved and the two fractions classified according to their particle size distribution. The fractions were subjected to an alkaline fusion activation pretreatment, and subsequently the crystallization reaction was carried out, varying the operating conditions in the appropriate range to obtain high conversions in both zeolite A and Zeolite X. After zeolitization, the two samples containing the highest zeolite A and zeolite X percentages were impregnated with the Anderson phase Co(III)Mo6 and tested as heterogeneous catalysts in the clean oxidation of diphenylsulfide (DFS) with H2O2. Results were expressed in terms of diphenylsulfoxide (DFSO) and diphenylsulfone (DFSO2) conversions. Supports and catalysts were characterized by X-ray powder diffraction, scanning electron microscopy and semi-quantitative analysis by electron microprobe (EDS), N2 adsorption isotherms and infrared spectroscopy. The nonimpregnated matrices presented conversion values for diphenyl compounds between 50 and 60% in 90 min of reaction. Comparing these materials with pure zeolites, all samples presented similar catalytic performances. The CoMo6 addition increased the conversion level at about 90% in 90 min of reaction, being 80% the proportion of DFSO2 obtained. It is concluded that zeolitized volcanic ashes could play a role in the preparation of catalysts for the eco-compatible oxidation of diphenylsulfides.