Miao Jiang

Single atom dispersed Rh-biphephos&PPh3@porous organic copolymers: highly efficient catalysts for continuous fixed-bed hydroformylation of propene

A vinyl functionalized biphephos ligand with high steric hindrance was copolymerized with tris(4-vinphenyl)phosphane and other ligands to afford efficient porous organic copolymers (POPs) through the solvothermal synthesis technique. By employing the copolymer self-supported heterogeneous Rh/CPOL-bp&P catalysts, the hydroformylation of propene to linear-butaldehyde can be performed efficiently in a continuous fixed-bed reactor with high regioselectivity (l/b > 24), activity (TOF > 1200 h−1) and stability (over 1000 h) under mild conditions (70 °C, 0.5 MPa), which represents a substantial improvement in the efficiency of this important industrial process. EXAFS and HAADF-STEM showed that the Rh was a single atom dispersion, which explained well the high efficiency of the Rh/CPOL-bp&P catalysts. Compared with liquid–liquid biphasic (LLB) and ionic liquid (IL) systems, this highly efficient solvent free system has the advantages of simple operability, and almost no waste emission, which meets the demands of green industrial processing.

Designing highly efficient Rh/CPOL-bp&PPh3 heterogenous catalysts for hydroformylation of internal and terminal olefins

Vinyl functionalized Biphephos ligand, denoted as vinyl biphephos, has been succesfully synthesized. Copolymerization of vinyl biphephos with tris(4-vinphenyl) phosphane can afford an efficient Porous Organic Polymer (POP), CPOL-bp&PPh3. The ultimately formed Rh/CPOL-bp&PPh3 heterogeneous catalyst showed excellent performance in converting terminal olefins to the corresponding linear aldehydes with high regioselectivity (l/b = 96u2006:u20064–98u2006:u20062), activity and stability, even better than the comparable homogeneous Rh + vinyl biphephos system. Notably, isomerizing hydrofromylation of internal olefins (2-heptene, 2-octene, trans-3-hexene) was also performed with high regioselectivity (l/b = 92u2006:u20068–93u2006:u20067) using the Rh/CPOL-bp&PPh3 heterogeneous catalyst.

Effect of different synthetic routes on the performance of propylene hydroformylation over 3V-PPh3 polymer supported Rh catalysts

This article studied the difference between two 3V-PPh3 polymer (POL-PPh3) supported Rh catalysts synthesized via different synthetic strategies, one-pot and post-synthesis, respectively. The catalytic performance of the two catalysts was further evaluated for the hydroformylation of propylene on a fixed-bed reactor. The catalyst prepared through post-synthesis (Rh/POL-PPh3) showed better catalytic activity compared to the one-pot sample (Rh–POL-PPh3), and exhibited excellent long-term stability. N2 sorption, SEM, EXAFS and FT-IR characterization results suggested that the possible reasons for the different catalytic performance of two catalysts can be ascribed to the fact that part of Rh species was probably embedded into the framework of POL-PPh3 in the Rh–POL-PPh3 catalyst. Moreover, it might restrict the accessibility of reagents to Rh species and block the flexible coordination between Rh species and POL-PPh3. The Rh/POL-PPh3 catalyst synthesized via post-synthesis and the Rh species were uniformly distributed on the surface of POL-PPh3, which might have a positive effect on the improvement of the mass transfer and the flexible coordination of Rh species with POL-PPh3.

The influence of impregnation sequence on glycerol hydrogenolysis over iridium-rhenium catalyst

A series of iridium-rhenium catalysts with different impregnation sequences were prepared and the catalytic properties of these catalysts for glycerol hydrogenolysis were evaluated. The catalyst prepared byxa0the impregnation of Ir prior to Re afforded the best selectivity to 1,3-propanediol of 49.2xa0% with 43.7xa0% glycerol conversion. These catalysts were also characterized by temperature programmed reduction (TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), NH3-temperature programmed desorption (NH3-TPD), Fourier transform infrared spectroscopy (FT-IR) and H2-chemisorption. It was found that Ir0 species played a key role on the activities of glycerol conversion, and Re species might act as an efficient promoter to improve the dispersive state of Ir species as well as the reducibility. Kinetic studies have also been conducted and it was observed that the number of Ir0 may affect the extent of consecutive hydrogenolysis of 1,3-propanediol over catalysts, and an appropriate number of Ir0 was of importance to 1,3-propanediol selectivity.

Rh catalysts supported on knitting aryl network polymers for the hydroformylation of higher olefins

Rh catalysts supported on knitting aryl network polymers (Rh/KAPs) were prepared for the hydroformylation of higher olefins. Rh catalysts supported on triphenylphosphine-benzene-base polymers (Rh/KAPs-1) showed higher activity for the higher olefins than Rh/SiO2 catalysts. Fourier transform infrared spectroscopy, thermogravimetry, N-2 adsorption-desorption, X-ray diffraction, transmission electron microscopy, C-13 NMR, and P-31 NMR showed that the Rh/ICAPs-1 catalysts have high thermal stability, high surface area, hierarchical porosity, highly dispersed Rh nanoparticles, and in situ formed homogeneous active species during the reaction

Ru coordinated with BINAP in knitting aryl network polymers for heterogeneous asymmetric hydrogenation of methyl acetoacetate

A facile method for the preparation of heterogeneous asymmetric hydrogenation catalysts was presented. BINAP was knitted with aryl compounds using formaldehyde dimethyl acetal (FDA) as a cross-linker by Friedel–Crafts reaction without any pre-modification. The prepared catalysts showed different catalytic activities, and excellent recyclablilty results could be achieved in asymmetric hydrogenation.

Alcohol-treated SiO2 as the support of Ir-Re/SiO2 catalysts for glycerol hydrogenolysis

Abstract The surface of SiO 2 support was pretreated by C1–C4 normal alcohols before the impregnation of iridium and rhenium precursors. These catalysts were applied in high concentration glycerol aqueous solution hydrogenolysis. The catalysts prepared from the pretreated supports exhibited high catalytic activity because of the formation of more active sites from a high dispersion of iridium oxide and rhenium oxide. The catalysts with the support pretreated by 1-propanol showed the highest glycerol conversion of 59.5%. The supports and catalysts were characterized by FT-IR, nitrogen adsorption, TPR, XRD, TEM, H 2 -chemisorption and NH 3 -TPD.

Effect of lengthening alkyl spacer on hydroformylation performance of tethered-phosphine modified Rh/SiO2 catalyst

Abstract Rh/SiO 2 catalysts with tethered-phosphines with different alkyl spacer lengths have been prepared, tested and characterized. Lengthening the alkyl spacer of the tethered-phosphine improved the flexibility of tethered-phospine, promoted the formation of active species and enhanced the activity of hydroformylation over other tethered-phosphine modified Rh/SiO 2 catalysts.