Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline

Selectively converting CO and H2 to gasoline product （isoparaffin and olefin） in one step still remains a great challenge. We demonstrate effective H-USY zeolite supported nano-cobalt bifunctional catalysts for this catalytic reaction, which are prepared by the novel physical sputtering process. Particles of the sputtered cobalt exist in nano-level and are well-dispersed on acid USY zeolite. Easy activation of the loaded nano-cobalt is also achieved in a low-temperature hydrogen reduction atmosphere. In the tandem catalytic reaction, the sputtered bifunctional Co/USY catalyst exhibits a much higher CO conversion and higher isoparaffin selectiv- ity than the conventional impregnated one. Compared with H-Mor, H-Beta and other zeolites supported catalysts, H-USY zeolite supported cobalt catalyst shows the clearest promotional effect on the activity of FischerTropsch synthesis. The described synthesis herein provides a new pathway to solve the problem caused by the strong metal-support interaction （MSI） in heterogeneous catalysis.

Effect of LaPO_(4) Introduction as a Vanadium Trap for Preventing USY Zeolite Destruction

The use of lanthanum phosphate as a vanadium trap for preventing destruction of USY zeolite was studied.The effect of deposited vanadium on the hydrothermal destruction of zeolite was investigated by the solid-state NMR technique.LaPO4 species can inhibit the zeolite framework structure from being collapsed by vanadium after steaming treatment.The EPR results show the oxidation-reduction reaction in LaPO4 and V2O5 system and inhibition of zeolite destruction by V5+.The catalysts prepared from USY and LaPO-USY zeolites were also tested in the catalytic reactions of heavy oil.The assessment results indicated that the USY modified with LaPO4 could bring about remarkably high dehydrogenation ability.

Formaldehyde oxidation on Pd/USY catalysts at room temperature: The effect of acid pretreatment on supports

The complete catalytic oxidation of formaldehyde (HCHO) to CO_(2)and H_(2)O at room temperature is a green route for indoor HCHO removal.Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area,intricate pores and high adsorption capacity.However,the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature.In this work,we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation.Activity tests illustrated that HCHO could be completely oxidized to CO_(2)and H_(2)O at a nearly 100%conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g·hr) at 25℃,when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L.The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction.The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene(DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.

Effect of Cu loading content on the catalytic performance of Cu-USY catalysts for selective catalytic reduction of NO with NH_(3)

Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method.The obtained catalysts were subjected to selective catalytic reduction of NOxwith NH_(3)(NH_(3)-SCR) performance evaluation,structural/chemical characterizations such as X-ray diffraction (XRD),N2adsorption/desorption,H_(2)temperature-programmed reduction (H_(2)-TPR),NH_(3)temperature-programmed desorption (NH_(3)-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption,NH_(3)adsorption and NO+O_(2)in situ reactions.Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with5 wt.%Cu) could be promising candidates with highly efficient NH_(3)-SCR catalytic performance,relatively low byproduct formation and excellent hydrothermal stability,although its SO_(2)poisoning tolerability needs alleviation.Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading.On one hand,Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH_(3)-SCR reactivity.On the other hand,higher Cu loading leads to depletion of Br?nsted acid centers and simultaneous formation of abundant Lewis acid centers,which facilitates NH_(4)NO_(3)reduction via NH_(3)adsorbed on Lewis acid centers,thus improving SCR reactivity.However,Cu over-introduction leads to formation of surface highly dispersed CuOx,causing unfavorable NH_(3)oxidation and inferior N2selectivity.