1,3-Butadiene Adsorption over Transition Metal Polycation Exchanged Faujasites

Abstract

New adsorbents for butadiene removal from liquid and gas streams, which are transition metal (Cu, Zn, Mn) polycation exchanged zeolites, were prepared on the basis of low-silica and dealuminated faujasites by ion exchange with the corresponding salt solutions at the conditions of their partial hydrolysis. Obtained samples were characterized by XANES, ESR, and DRIFT spectroscopy along with equilibrium and dynamic adsorption studies. It is shown that transition metal polycation containing faujasites significantly surpass monocation analogues with respect to butadiene adsorption capacity. It is also found that an enhanced ability to adsorb butadiene is peculiar to faujasites with strong acidity that defines the activity of the adsorbent in the oligomerization of adsorbed butadiene. The suggested adsorbents are fully regenerable at gradual elevation of regeneration temperature up to 250–350 °C.

Reactive Adsorption of Sulfur Compounds on Transition Metal Polycation‐Exchanged Zeolites for Desulfurization of Hydrocarbon Streams

“…. As the TrM polycation‐exchanged zeolite along with the polycations contain significant amounts of monocations, a relatively low change of the average Cu−O distance in the (Cu) p CaLSF sample versus the monocation Cu‐exchanged zeolites may give evidence of an essential increase of the reactivity of the Cu polycations.…”

“…[11,19,20] Thea uthors also found that the reactive adsorption of 1,3-butadiene with the dimerization of the substrate over some Tr Mp olycation-exchanged low-silica faujasites (LSF) is responsible for the enhanced adsorption capacity of the applied adsorbent-catalysts. [21] Accordingly, it is reasonable to assume that the unusually high adsorption values for sulfur compounds displayed by Cu, Zn, and Mn polycation-exchanged zeolites [22,23] may result from as imilar catalytic-adsorption action. Thep resented inveistedi sd evoted to the study of the mechanism of the reactive adsorption of sulfur compounds by Tr Mp olycationexchanged zeolites and the clarification of the characteristic oxidizing role of the adsorbent-catalystsi nd esulfurization of gas and liquid hydrocarbonstreams.…”

“…Owing to the high dispersity and nanostructures of the TrM polycation moieties (0.4–1.6 nm) along with the excess of oxygen in the TrM superoxides, remarkable adsorption capacities and catalytic activities of the corresponding zeolites towards various substances were reported . The authors also found that the reactive adsorption of 1,3‐butadiene with the dimerization of the substrate over some TrM polycation‐exchanged low‐silica faujasites (LSF) is responsible for the enhanced adsorption capacity of the applied adsorbent–catalysts …”

“…The Cu K‐edge X‐ray absorption near‐edge structure (XANES) spectra for fresh (Cu) p CaLSF samples and those treated with 1‐butanethiol showed that the energy position of the Cu K‐edge and the intensity of the white line in the spectra of both samples are similar to those of the CuO reference. This confirms the previous result that the (Cu) p CaLSF adsorbent–catalyst contains copper species in the 2 + electronic state, and the charge of the Cu 2+ cations remains unchanged after completion of the thiol oxidation reactions.…”

“…Theo btained average interatomic CuÀOd istance in the original (Cu) p CaLSF sample of 2.0 is slightly higher than the similar crystal-structure parameter for the monocation Cu-exchanged zeolites and CuO oxide,w hich are equal to 1.95-1.97 according to Refs. [36,37].A st he Tr Mp olycation-exchanged zeolite along with the polycations contain significant amountso fm onocations, [21,22] ar elatively low change In such am anner, itw ould be reasonable to expect ap erceptible decreaseo ft he CuÀOd istancei nt he adsorbent-catalyst after the thiol oxidation. Nonetheless,t he obtained results in Table 4d on ot confirm this expectation for unclear reasons.H owever, the EXAFS data demonstrate the essential decrease of the average surface area occupied by Cu 2+ + cations (s)a nd, more importantly,a na ppreciable reduction of the oxygenc ontent in the (Cu) p CaLSF catalyst as ar esult of the thiolo xidation.…”