Xiangen Song

Effect of Al2O3 Promoter on a Performance of C1–C14 α-Alcohols Direct Synthesis over Co/AC Catalysts via Fischer–Tropsch Synthesis

The influence of Al2O3 promoter on a performance of C1–C14 α-alcohols direct synthesis from syngas over activated carbon (AC) supported cobalt catalysts (Co/AC catalysts) was investigated using CO hydrogenation evaluation, XRD, HRTEM, H2-TPR, pulsed CO chemisorption, H2-TPD and N2 physisorption techniques. The results obtained showed that the addition of Al2O3 increased significantly the Co component dispersion without remarkably decreasing its reducibility and inhibited its aggregation during reaction, resulting in greatly enhanced reaction activity as well as increased selectivity towards liquid products. Appropriate amounts of Al2O3 can promote the formation of Co2C, leading to an increase of total alcohol fraction in the liquid products. Moreover, the Al2O3 addition can further promote the formation of higher alcohols (C6–C14 alcohols).Graphical Abstract

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.

Synthesis of Mixed Alcohols from CO Hydrogenation over Iron and Nickel Metal Phosphide Catalysts

A series of silica supported iron and nickel metal phosphides with different molar ratios of P to metal were synthesized by the temperature programmed reduction method. Their catalytic performance for CO hydrogenation in a fixed bed reactor was tested with the conditions of 553 K, 5.0 MPa, and H2:CO = 2 (molar ratio). With the FePx/SiO2 catalysts (x denotes the molar ratio of P to metal), the product was a mixture of oxygenates containing methanol as the major component. With the NiPx/SiO2 samples, the liquid product was mainly methanol. The Fe2P, Fe3P, Ni, Ni2P, Ni3P, and Ni12P5 phases were stable during CO hydrogenation, while most of the metallic Fe phase transformed into iron carbide.

Study on the effect of alkali promoters on the formation of cobalt carbide (Co2C) and on the performance of Co2C via CO hydrogenation reaction

The present investigation deals with an alkali metal assisted synthesis of cobalt carbide (Co2C), starting from carburizing reduced complex precursors (obtained from Co3O4 with the addition of Li2O, Na2O and K2O) using CO as a carburization source. It is found that the Co2C formation could be significantly accelerated by the Li component. A comparative study reveals that the promotion effect of Li component may be related to the H2 adsorption on the reduced precursor, which enhanced the ability of the precursor to react with CO. Furthermore, the Co2C prepared from the precursor containing Li component shows a considerable increase in activity for CO hydrogenation and an improved fraction of higher alcohols in the total alcohol products, compared to the Co2C prepared without promoters. An attempt is made to elucidate the catalytic behavior of the as-prepared Co2C samples.

Fischer-Tropsch synthesis: Characterizing and reaction testing of Co2C/SiO2 and Co2C/Al2O3 catalysts

SiO2- and Al2O3-supported CO2C catalysts were prepared by carburizing supported Co precursors with CO. The catalysts were characterized by N-2 physisorption, X-ray diffraction and H-2 temperature-programmed reduction techniques, and evaluated by the Fischer-Tropsch (F-T) reaction. The results showed that SiO2- and Al2O3-supported Co2C catalysts could be successfully obtained but sufficient carburization time was required. All of the as-prepared supported Co2C catalysts exhibited activity and selectivity towards alcohols. It is considered that surface metallic Co species contributed to the activity, surface Co2C species were responsible for the formation of alcohols, and bulk CO2C species were inert during the F-T reaction

Ru–PPh3@porous organic polymer: efficient and stable catalyst for the trickle bed regioselective hydrogenation of cinnamaldehyde

Ru supported on the porous vinyl-functional triphenylphosphine organic polymer (Ru–PPh3@POP) as a heterogeneous catalyst for the selective hydrogenation of cinnamaldehyde (CAL) was synthesized. This catalyst, which combines the advantages of heterogeneous and homogeneous catalyst, showed much higher catalytic activity of continuous trickle bed hydrogenation of CAL than traditional inorganic material supported heterogeneous catalysts. The high efficiency of the Ru–PPh3@POP catalyst was attributed to the formation of the strong coordination bonds between the Ru species and the exposure phosphorus atoms on the surface of PPh3@POP support according to the results of EDS-mapping, 31P NMR, XPS analysis and HRTEM. Importantly, Ru species maintained their nanoparticles without further aggregation during the long-term reaction, and thus the catalyst exhibited a high conversion of CAL of 55% and selectivity towards cinnamyl alcohol (COL) of 63% even over 312xa0h of time on stream of hydrogenation of CAL. The ICP results of the reaction solution revealed that there was no Ru leaching from the PPh3@POP support during the continuous reaction process. This excellent catalytic activity and stability make it very attractive. Our approaches provide a methodology to expand the heterogenized homogeneous catalysts widely spread in exploitation in fine chemical industries.

Catalytic hydrogenation of carbon monoxide over Rh–Mn–Li/SiO2 catalyst for the synthesis of C2+ oxygenates: the remarkable effect of urea on the particle size of Rh

A series of Rh–Mn–Li/SiO2 catalysts were prepared by the impregnation of a silica support with solutions containing metal precursors with different amounts of urea. Catalyst performance was investigated by the hydrogenation of carbon monoxide. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, hydrogen chemisorption, diffuse reflectance ultraviolet–visible (DR UV–Vis) spectroscopy, and thermogravimetric analysis. The results revealed that the amount of urea had a significant effect on the particle size of Rh, which increased from approximately 2–5xa0nm with the increase in urea loading from 0 to 2.0xa0wt%. DR UV–Vis spectra indicated that the increase in the Rh particle size with increasing urea loading might be attributed to the coordination of Rh3+ with urea or its derivatives during calcination. At a urea loading of 1.0xa0wt%, the particle size of Rh was 3.7xa0nm, and the space time yield of C2+ oxygenates reached a maximum of 560.0xa0gxa0kg−1xa0h−1.

Effect of Catalyst Preparation on Hydroisomerization of n-Heptane over Pt/Silicalite-1

The isomerization of n-heptane was comparatively investigated over Pt catalysts prepared by deposition (Pt/S-1-DP) and impregnation precipitation (Pt/S-1-IMP) method with a low loading, separately. It was found that Pt/S-1-DP catalyst produced a much higher catalytic conversion compared with the counterpart catalyst prepared by impregnation. Combined with various characterization techniques, the better performance over Pt/S-1-DP was attributed to not only the well improved dispersity and the smaller size of Pt particles but also the faster transfer of reactive species between Pt sites and acid sites. The activity could be improved by increasing the reduction temperature. Moreover, the (de)hydrogenation of Pt over Pt/S-1 catalyst was verified by in situ infrared spectroscopy through H/D isotope exchange experiment.Graphical Abstract