Enhanced hydrodeoxygenation of lignin-derived anisole to arenes catalyzed by Mn-doped Cu/Al_(2)O_(3)

Lignin is a renewable carbon resource to produce arenes due to its abundant aromatic structures.For the liquid-phase hydrodeoxygenation(HDO)based on metallic catalysts,the preservation of aromatic rings in lignin or its derivatives remains a challenge.Herein,we synthesized Mndoped Cu/Al_(2)O_(3) catalysts from layered double hydroxides(LDHs)for liquid-phase HDO of lignin-derived anisole.Mn doping significantly enhanced the selective deoxygenation of anisole to arenes and inhibited the saturated hydrogenation on Cu/Al_(2)O_(3).With Mn doping increasing,the surface of Cu particles was modified with MnO_(x) along with enhanced generation of oxygen vacancies(Ov).The evolution of active sites structure led to a controllable adsorption geometry of anisole,which was beneficial for increasing arenes selectivity.As a result,the arenes selectivity obtained on 4Cu/8Mn4AlO_(x) was increased to be more than 6 folds of that value on 4Cu/4Al_(2)O_(3) over the synergistic sites between metal Cu and Ov generated on MnO_(x).

Hydroformylation of formaldehyde to glycolaldehyde:An alternative synthetic route for ethylene glycol

Hydroformylation of formaldehyde to glycolaldehyde(GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol(EG),shows great advantages in the aspects of the process complexity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavourable,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal complex catalysts(including central metals and ligands),reaction conditions(e.g.,temperature,pressure,formaldehyde source and solvent)and promoters.Furthermore,the reaction mechanisms,involving neutral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief overview of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mechanisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.

Regulating electronic environment on alkali metal-doped Cu@NS-SiO_(2) for selective anisole hydrodeoxygenation

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure.Herein,we synthesized a series of novel Cu-based catalysts,Cu@NS-SiO_(2)(NS=nano sphere)and alkali metals(Na,K,Rb,and Cs)doped Cu@NS-SiO_(2),and applied them in hydrodeoxygenation reaction of anisole.High Cu dispersion was presented on all catalysts.The modification of alkali metals on Cu@NS-SiO_(2) significantly enhanced the electron density of Cu sites in the following order:Cs>Rb>K>Na,among which Cs decreased the Cu_(2)p_(3)/2 binding energy most(by 0.7 eV).Moreover,the modification did not substantially affect the geometric structure of Cu species.This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole,and thus promoted the selectivity of benzene.Compared with Cu@NS-SiO_(2)(~59%),the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO_(2) at~83%.

Hydroformylation over polyoxometalates supported single-atom Rh catalysts

Atomic dispersion of Rh on phosphotungstic acid(PTA)salts was achieved by a self-assembled precipitation method using alkali metal ions as coprecipitation reagents.During styrene hydroformylation,the supported Rh single-atom catalyst(Rh1/M-PTA,M refers to an alkali metal ion)demonstrated an optimum turnover frequency(TOF)of 1076 h−1.With increasing ionic radius,the pore size of the catalysts increased in the following order:Rh1/K-PTA<Rh1/Rb-PTA<Rh1/Cs-PTA.The catalytic activity showed the same trend,suggesting a positive correlation between pore size and hydroformylation perfor-mance.Further experimental data suggested that temperature is an important factor affecting not only the activity but also the selectivity.This study enriches the understanding of the structure and catalytic properties of PTA-supported single-atom materials.The cation-controlled synthesis of catalysts may also be applied to prepare other single-atom catalysts with tunable pore size distributions.

Effects of bile salts and divalent cations on the adsorption of norfloxacin by agricultural soils

The effects of bile salts （sodium cholate and sodium deoxycholate, 0-20 mmol/L）, divalent cations （Ca^2＋, Mg^2＋, Cu^2＋ and Zn^2＋, 0-20 mmol/L） or pH （3.0-10.0） on the adsorption of norfloxacin by three selected soils （Paddy_H, Paddy_G and Red_J） were systematically studied. Soil adsorption of norfloxacin follows a pseudo second-order kinetics model, and the maximum adsorption capacity has been determined from the nonlinear fit of the Langmuir isotherm model to be 88.8, 88.1 and 63.0 μmol/g for the adsorption onto Paddy_H, Paddy_G and Red_J, respectively. The results indicate that norfloxacin has a high adsorption affinity for the agricultural soils tested and that the organic content of these soils have at least a slight influence on this adsorption. The adsorption of norfloxacin to soils was strongly dependent on pH and exhibited a maximum at approximately pH 6. The presence of divalent cations prominently suppressed the adsorption of norfloxacin by paddy soils, which followed an order of Cu^2＋ 〉 Mg^2＋ 〉 Ca^2＋ 〉 Zn^2＋, and by red soil, which followed an order of Cu^2＋ 〉 Zn^2＋ 〉 Ca^2＋ 〉 Mg^2＋. The adsorption of norfloxacin （by the soils studied） sharply decreased as the amount of bile salts was increased. For uncharged norfloxacin at environmentally relevant pH values, such factors as soil type, exogenous divalent cations and macromolecules significantly altered the environmental fate and transport of norfloxacin between aquatic and soil interfaces.