Rh-based homogeneous catalysts with phosphine ligands are highly active in hydroformylation reactions. Using DFT calculations, we found a similar electronic effect of inorganic phosphorus in the Rh2P structure. The energy profiles demonstrated that Rh2P would significantly enhance the styrene hydroformylation activity in comparison with Rh, which was further confirmed by experiments. Triphenylphosphine (PPh3) was used as the phosphorus source, and Rh2P supported on silica was prepared by impregnation at a relatively low temperature (550 °C). The turnover frequency (TOF) of styrene hydroformylation was increased to 1496 h–1, which was comparable with some single atom catalysts (SACs). Recycling tests showed a good stability in five runs. Furthermore, HAADF-STEM, XPS, and other characterizations confirmed the synthesis of the Rh2P structure. The promotion effect of P was bifunctional. On the one hand, the doped P separated the surface Rh atoms, which eliminated the surface hollow sites and prevented excessively strong adsorption of the reactants. On the other hand, electrons transferred from Rh to P, causing the surface Rh atoms to be positively charged, which was favorable for hydroformylation reactions. The geometric effects improved the dispersion and the electronic effects changed the rate-determining step from CO insertion to phenylpropionyl hydrogenation, both leading to a higher hydroformylation activity.

Graphene oxide (GO) is a type of twodimensional nanomaterial with a single-atom thickness. GO sheets contain pristine regions, oxidized regions, and a small fraction of holes. By stacking GO sheets together, a GO membrane can be fabricated with sufficient mechanical strength. The interlayer nanocapillary network formed from connected interlayer spaces, together with the gaps between the edges of noninterlocked neighboring GO sheets and cracks or holes of the GO sheet, provides passage for molecules or ions to permeate through the GO membrane in an aqueous solution. The characteristics of molecules or ions (e.g., their size, charge, and the interaction with the GO membrane) affect the separation performance of the GO membrane. The contribution of gaps between neighboring GO sheets for separation can be adjusted by changing the GO sheet size and the GO membrane thickness. The interlayer space of the GO membrane can be adjusted by changing the water pH and modifying or reducing the GO sheets to obtain the desired separation performance. The production of the GO membrane is easily scalable and relatively inexpensive, indicating that the GO membrane has promising potential for applications such as water treatment, desalination, anticorrosion, chemical resistance, and controlled release coatings.

Rh-based bimetallic catalysts are promising ligandfree heterogeneous catalysts for hydroformylation reactions. It is important to understand the mechanism of this bimetallic promotion for designing highly selective and active heterogenous catalysts. In this work, the RhCo bimetallic catalyst was investigated focusing on the promotion effect of Co for the gasphase hydroformylation of ethene. Adding Co to Rh increased both the catalytic productivity and selectivity to oxygenates. In situ diffuse reflectance infrared Fourier transform spectroscopy and CO-temperature programmed desorption were used to characterize CO adsorption. The results showed that the addition of Co to Rh changed the CO adsorption modes and strength for the Rh-based catalyst. Modulated CO adsorption strength was important to enhance selectivity. Density functional theory calculations were carried out to reveal the reaction mechanism. A reaction pathway was proposed to clarify the reason for enhanced selectivity on a RhCo bimetallic catalyst and show that the ratio between CO migration and desorption played a great role in this reaction.

The development of a highly active heterogeneous catalyst for styrene hydroformylation is a major challenge, and we previously found that Rh2P was a good candidate. By doping a second metal of Co, we further improved the activity by 1.7 times, and the highest TOF reached 2563 h–1 on Rh7Co1P4/SiO2. The addition of Co tuned the electronic environment of surface Rh atoms without changing the crystal structure, and the reaction activity showed a volcano relationship with the Co ratio. DFT calculations showed that Co doping decreased the overall activation energy of surface reactions and destabilized H2 adsorption simultaneously. When x ≤ 2 for Rh8–x Co x P4/SiO2 catalysts, surface Rh atoms had positive valence and H2 adsorption was exothermic. Therefore, the hydroformylation rate was mainly determined by surface reaction with a first order of styrene concentration. When x > 2, however, surface Rh atoms were negatively charged and H2 adsorption became thermodynamically unfavorable. The reaction activity was then determined by H2 adsorption and was independent of styrene concentration. We introduced δE, which was the sum of overall activation energy and H2 coadsorption energy with styrene, to predict activity. Moderate addition of Co decreased the value of δE and promoted the activity, while excessive doping would increase δE.

For supported metal catalysts, subsurface sites can significantly influence the adsorption and reaction behaviors on surface sites via the electronic effect and geometric effect. Subsurface carbon in PdC x has been proven to be an effective selectivity promoter in acetylene semihydrogenation. Herein, we theoretically calculated the reaction trajectory on Ni3ZnC0.7 and designed a metal–organic framework-layered hydroxide salt-derived synthesis strategy for the Ni3ZnC0.7/C catalyst. The formation of the flake-like Ni3ZnC0.7 phase was monitored by in situ X-ray diffraction (XRD) and confirmed by XRD, transmission electron microscopy, and selected area electron diffraction characterizations. In acetylene semihydrogenation, the Ni3ZnC0.7/C catalyst had 85% ethylene selectivity even at 100% acetylene conversion, supporting the conclusions from density functional theory calculations. The green oil selectivity was controlled below 2%. All results indicated that incorporating carbon atoms in the subsurface sites significantly enhanced the ethylene selectivity in acetylene semihydrogenation.