Role of intrinsic defects on carbon adsorbent for enhanced removal of Hg^(2+)in aqueous solution

Carbon is a normally used adsorbent for removal of heavy metal ion in aqueous solutions,but the efficient adsorbent needs intensive modification by heteroatom doped or supported noble metals that cause severe pollution and easy leaching of active components during use.In this paper,the role of intrinsic defects on Hg^(2+)adsorption for carbon adsorbent was investigated.The maximum adsorbing capacity of defectrich carbon has been improved up to 433 mg·g^(-1)which is comparable to most of the modified carbon adsorbents via supported metal chloride or noble metal components.The basicity is increased with the content of defective sites and the strong chemical bonding can be formed via electron transformation between the defect sites with adsorbed Hg^(2+).The present study gives a direction to explore cheap and easily scale-up high-performance mercury adsorbents by simply tuning the intrinsic defective structure of carbon without the necessity to support metal or other organic compounds.

Wheat flour-derived N-doped mesoporous carbon extrudes as an efficient support for Au catalyst in acetylene hydrochlorination

We recently reported an N‐doped mesoporous carbon(N‐MC)extrudate,with major quaternary N species,prepared by a cheap and convenient method through direct carbonization of wheat flour with silica,which has excellent catalytic performance in acetylene hydrochlorination.Herein,we examined the activity of Au supported on N‐MC(Au/N‐MC)and compared it with that of Au supported on nitrogen‐free mesoporous carbon(Au/MC).The acetylene conversion of Au/N‐MC was 50%at 180°C with an acetylene space velocity of 600 h–1 and VHCl/VC2H2 of 1.1,which was double the activity of Au/MC(25%).The introduced nitrogen atoms acted as anchor sites that stabilized the Au3+species and inhibited the reduction of Au3+to Au0 during the preparation of Au/N‐MC catalysts.

Dual active sites over Cu-ZnO-ZrO_(2) catalysts for carbon dioxide hydrogenation to methanol

CO_(2) hydrogenation to methanol is a significant approach to tackle the problem of global warming and simultaneously meet the demand for the portable fuel.Cu-ZnO catalysts with various kinds of promoters have received wide attention.However,the role of promoter and the form of active sites in CO_(2) hydrogenation are still in debate.Here,various molar ratios of ZrO_(2) were added into the Cu-ZnO catalysts to tune the distributions of Cu^(0) and Cu+species.A volcano-like trend between the ratio of Cu+/(Cu++Cu^(0))and the amount of ZrO_(2) is presented,among which the CuZn10Zr(the molar ratio of ZrO_(2) is 10%)catalyst reaches the highest value.Correspondingly,the maximum value of space-time yield to methanol with 0.65 gMeOH/(gcat·hr)is obtained on CuZn10Zr at reaction conditions of 220°C and 3 MPa.Detailed characterizations demonstrate that dual active sites are proposed during CO_(2) hydrogenation over CuZn10Zr catalyst.The exposed Cu^(0) takes participate in the activation of H_(2),while on the Cu^(+) species,the intermediate of formate from the co-adsorption of CO_(2) and H_(2) prefers to be further hydrogenated to CH_(3)OH than decomposing into the by-product of CO,yielding a high selectivity of methanol.