Preparation of Ultradispersed Crystallites of Modified Natural Clinoptilolite with the Use of Ultrasound and Its Application as a Catalyst in the Synthesis of Methyl Salicylate

Abstract

The ultradispersed crystallites (300 – 325 nm) of the acid modified natural clinoptilolite (CL, ν(SiO2)/ν(AI2O3) = 8.9) from Dzegvi (Georgia) deposit with the use of simplest method – of the indirect effect of ultrasound – were prepared. Under the influence of ultrasound the happening changes of structure and the sizes of clinoptilolite particles are shown, by the XRD, FTIR spectroscopy and by means of laser particle size analyzer, respectively. Catalytic activities of the initial acid form of the clinoptilolite (H–CL, ν(SiO2)/ν(AI2O3) = 23.3) and its form processed by ultrasound (H–CL (UlS)) in reaction of esterification of salicylic acid by methanol into methyl salicylate were compared. The indirect irradiation with ultrasound of acid form of clinoptilolite has led to sharp improve its catalytic properties in the formation of methyl salicylate. The best catalytic performance is achieved with ultrasound treated catalyst. The conversion of the salicylic acid and the selectivity to methyl salicylate on H–CL (UlS) were very high, 90 and 95%, respectively, at 120°C.