Effect of the Time of Acid-Thermal Modification of Clinoptilolite on Its Structure-Adsorption Characteristics

Abstract

Представлены и проанализированы литературные данные по влиянию различных факторов кислотной обработки на величину удельной поверхности клиноптилолитов различного происхождения, а также наши результаты по изучению влияния продолжительности кислотно-термального модифицирования отечественного природного клиноптилолита на его структурно-адсорбционные свойства. Установлено, что значения удельной поверхности кислотно-модифицированных образцов клиноптилолита, рассчитанные по адсорбции паров воды и по тепловой десорбции аргона, выше, чем в случае природного клиноптилолита. Ключевые слова: природный и кислотно-модифицированный клиноптилолит, структурно-адсорбционные свойства, удельная поверхность.

Acid-modified clinoptilolite as a support for palladium–copper complexes catalyzing carbon monoxide oxidation with air oxygen

“…From literature [6–16], it can be seen that a specific surface for acid-modified clinoptilolite significantly depends on an acid concentration, time and multiplicity of treatments, and a solid:liquid ratio. As a rule, S sp increased or attained its maximum value with an acid concentration and only once (S sp determination based on water vapor adsorption) [12], it decreased from 383 to 273 m 2  g −1 when C HCl was heightened from 0.16 to 5.0 mol L −1 at the temperature of 100 °C.…”

“…It is also used as an acid catalyst in oil processing and a support for catalytically active phase in the case of catalysts for redox reactions of CO, SO 2 , and O 3 [1–6]. Catalytic activity of clinoptilolite supported palladium–copper complexes has been found to depend considerably on physicochemical properties and structural parameters of a support affecting a composition of these surface complexes [4, 5].…”

“…For instance, Ni 2+ /CLI is applied for sulphur removal from fuel oil [18], Ag + /CLI [20], Cu 2+ (Zn 2+ , Mn 2+ )/CLI [21], Mn 2+ (Co 2+ , Cu 2+ )/CLI [22, 23] are used for ozone decomposition, K 2 PdCl 4 –Cu(NO 3 ) 2 –KBr/H-CLI and CuCl 2 /CLI are proposed by us for the oxidation of carbon monoxide [4–6, 24] and sulfur dioxide [25], respectively.…”

“…Although natural zeolites, including clinoptilolite, are commonly used for water vapor adsorption [26–28], adsorption of water vapor by clinoptilolite modified with acid [1, 12, 26] or transition metal ions (complexes) [6, 29, 30] is little-studied. However, it has been found by us [31, 32] that a composition and catalytic performance of surface palladium–copper complexes in some redox processes, namely, carbon monoxide and phosphine oxidation, significantly depend on a thermodynamic activity of water adsorbed on them ( = P/P S ).…”

Effect of Both the Phase Composition and Modification Methods on Structural-Adsorption Parameters of Dispersed Silicas

“…Those kinds of treatment result in changes in the structural-adsorption parameters and the physicochemical properties of supports, particularly in their water vapor adsorption capacities. These changes are well-examined in supports such as clinoptilolites and bentonites [21,22], however they are quite unexplored in the case of tripolis. Natural tripolis of different origins differ in their phase compositions and main phase ratios, and these parameters undoubtedly would change in their modified forms.…”