Zi-Sheng Chao

High-efficiency catalytic performance over mesoporous Ni/beta zeolite for the synthesis of quinoline from glycerol and aniline

A green route for the vapor-phase synthesis of quinoline from glycerol and aniline was developed in this work, employing Ni/mesoporous beta zeolite (denoted as Ni/Hβ-At) as a catalyst. The mesoporous beta zeolite was prepared by alkaline treatment. Various influencing factors were systematically investigated. Both mesopores and the type of acid sites of the catalyst played important functions in catalytic activity for the synthesis of quinoline. Mesopores facilitated the transport of bulky products from internal surface of the catalyst. Meanwhile, weak Bronsted acid sites favored the dehydration of glycerol to acrolein and the existence of Lewis acid sites could accelerate the formation of quinoline. The Ni/Hβ-At catalyst exhibited the highest catalytic activity; and as high as a 71.4% yield of quinoline was obtained under the optimized reaction conditions. An enhanced ability of anti-deactivation was also displayed, due to the existence of mesopores on the Ni/Hβ-At catalyst facilitating the transport of bulky products and restraining the deposition of the coke. Meanwhile, it was found that the coke was main reason leading to catalyst deactivation and its performance was basically regenerated. The catalytic properties were slightly lower after 3 reaction–regeneration cycles. Finally, a feasible reaction pathway was proposed on the basis of the various products.

Hydrogenation of 3-hydroxypropanal to 1,3-propanediol over a Cu–V/Ni/SiO2 catalyst

A Ni-based catalyst modified with copper and vanadium (5Cu–20V/30Ni/SiO2) was synthesized and employed in the hydrogenation of 3-hydroxypropanal (3-HPA) to 1,3-propanediol (1,3-PDO). Catalysts were systematically characterized via XRD, TEM, HRTEM, SAED, H2-TPD, N2 physisorption, H2-TPR, and XPS. It was indicated that the addition of Cu and V not only promoted the reduction of Ni2+ species and the generation of active hydrogen species, but also increased the dispersion of Ni species and the interaction between Ni particles and SiO2. The catalytic performance evaluation showed that the (5Cu–20V/30Ni/SiO2) could provide the largest yield of 1,3-PDO (above 76.8%) and highest TOF (4.32 × 103 s−1). The structure–activity relationship was clarified according to the characterization results. The optimized reaction conditions over the 5Cu–20V/30Ni/SiO2 catalyst were obtained as the reaction temperature of 80 °C, a H2 pressure of 2.0 MPa (H2), and an LHSV of 0.4 h−1. The employment of non-noble metals, the relatively low pressure of H2, and the relatively high yield of 1,3-PDO make 5Cu–20V/30Ni/SiO2 an efficient and economic catalyst that may have potential applications in industry.

UV‐Resistant and Thermally Stable Superhydrophobic CeO2 Nanotubes with High Water Adhesion

A novel type of sticky superhydrophobic cerium dioxide (CeO2 ) nanotube material is prepared by hydrothermal treatment without any chemical modification. A water droplet on the material surface shows a static water contact angle of about 157° but the water droplet is pinned on the material surface even when the material surface is turned upside down. Interestingly, the as-prepared CeO2 nanotube material displays durable superhydrophobicity and enhanced adhesion to water under ultraviolet (UV) light irradiation. Importantly, this change in water adhesion can be reversed by heat treatment to restore the original adhesive value of 20 µL. Further, the maximum volume of the water droplet adhered on the material surface of CeO2 nanotubes can be regulated without loss of superhydrophobicity during the heating treatment/UV-irradiation cycling. Meanwhile, the superhydrophobic CeO2 nanotube material shows remarkable thermal stability even at temperatures as high as 450 °C, long-term durability in chemical environment, and air-storage and good resistance to oily contaminant. Finally, the potential application in no-loss water transportation of this sticky superhydrophobic CeO2 material is demonstrated.

Synthesis of poly(L-lactide)/β-cyclodextrin/citrate network modified hydroxyapatite and its biomedical properties

Hydroxyapatite (HA) was modified by the chelation of citric acid and Ca2+ on the surface of HA, followed by cross-linking between the hydroxyl groups of β-cyclodextrin (β-CD) and citrate, and then further in situ ring-opening polymerization of L-lactide over the hydroxyl groups. The modification of HA adjusted its surface properties and reduced the particle size. The synthesized PLA-CD-HA-72 exhibited the good adhesion of mesenchymal stem cells (MSCs) of Wistar rats, higher viability of MSCs and larger osteoinductivity. The results indicated that the PLA-CD-HA-72 possessed a rather large biocompatibility and bioactivity, and it could be a promising candidate as a bone tissue engineering material.

Synthesis of a ZSM-5/NaA hybrid zeolite membrane using kaolin as a modification layer

Considering the reliable characteristics and the suitable silica alumina content of kaolin, a new way of synthesizing a ZSM-5/NaA hybrid zeolite membrane on 170 mm length ceramic tubes by employing kaolin as a modification layer using a hydrothermal synthesis process was presented for the first time in this work. Kaolin was filtrated on the surface of the support (not only the ceramic tube, but also the NaA membrane layer) as a modification layer not only promoting the interface interlinkage among the support, NaA membrane and ZSM-5 membrane layer, but also promoting the growth of zeolite membranes. The SEM and XRD results showed that compact and homogeneous NaA and ZSM-5 zeolite layers were both formed with the thicknesses being 7.06 μm and 6.14 μm, respectively, after modification with kaolin. The permeation separation experiments demonstrated that the performance of the ZSM-5/NaA hybrid membrane was better than that of the monolayer zeolite membrane with permselectivities of H2 over CO2, N2, CO and CH4 of 5.40, 4.65, 4.70 and 3.93, respectively, which were higher than the corresponding Knudsen diffusion coefficients. Above all, modifying the support with kaolin and then synthesizing the ZSM-5/NaA hybrid membrane could strengthen the performance of the zeolite membrane effectively, which provided a new approach for the synthesis of high performance zeolite membranes in the field of membrane separation.

Heterogeneous catalytic synthesis of quinoline compounds from aniline and C1–C4 alcohols over zeolite-based catalysts

The synthesis of quinolines from aniline and a C1–C4 alcohol was conducted under gas-phase reaction conditions over a series of zeolite-based catalysts. The texture and acid properties of catalysts were characterized by XRD, FT-IR, BET and NH3-TPD techniques. It was found that the total yield of quinolines was positively related to the relative content of Lewis acid sites of the catalyst. Among others, the ZnCl2/Ni-USY-acid catalyst possessed the best performance. Over this catalyst, the reactions of aniline and most of the alcohols provided a 42.3–79.7% total yield of quinolones under mild conditions, however, those of aniline and methanol, ethanol and iso-propanol predominantly led to N-alkylanilines. Furthermore, the reaction pathways for synthesizing quinolines via aniline reacting with polyhydric alcohols or monohydric alcohols was proposed in our work.

Synthesis of quinolines from aniline and propanol over modified USY zeolite: catalytic performance and mechanism evaluated by in situ Fourier transform infrared spectroscopy

The reaction of aniline and propanol to quinolines was conducted in a fixed-bed flow-type reactor, using a series of modified USY zeolite catalysts. The structural, textural and acidic properties of the catalyst were characterized by XRD, N2-physisorption, 27Al MAS NMR, NH3-TPD and pyridine-FTIR, while the mechanism for the reaction of aniline and propanol was investigated by in situ FTIR. It was identified that the reaction of aniline and propanol generated predominantly quinolines, including 2-ethyl-3-methylquinoline and other alkyl quinoline, N-alkyl aniline and other byproducts. Among others, the ZnCl2/Ni-USY catalyst exhibited the best performance, providing a 96.4% conversion of aniline and a 78.3% total yield of quinolines with 81.2% total selectivity to quinolines and 60.1% selectivity to 2-ethyl-3-methylquinoline at 683 K. This was attributed to the larger concentration ratio of Lewis acid sites to Bronsted acid sites over the ZnCl2/Ni-USY catalyst, relative to other catalysts. There were predominantly two possible routes for the formation of quinolines, which required predominantly Lewis acid sites and Bronsted acid sites, respectively. In both the routes, N-phenylpropan-1-imine was proposed as the key intermediate. Relative to that based on Bronsted acid sites, the route based on Lewis acid sites appeared to contribute much more in the generation of quinolines from the reaction of aniline and propanol.

Hydrogenation of 3-hydroxypropanal into 1,3-propanediol over bimetallic Ru–Ni catalyst

A series of Ni-based catalysts, including Ru/SiO2, Ni/SiO2 and Ru–Ni/SiO2, were prepared and employed in the hydrogenation of 3-hydroxypropanal (3-HPA) to 1,3-propanediol (1,3-PDO). The catalysts were systematically characterized by means of XRD, TEM, HRTEM, SEAD, XPS, H2-TPD, H2-TPR and N2-physisorption. It was indicated that the introduction of Ru onto the Ni/SiO2 not only increased the porosity of catalyst and the degree of dispersion of Ni species but also promoted the reduction of Ni2+ to Ni0 and the generation of active hydrogen species. The catalytic performance evaluation showed that the Ru–40Ni/SiO2 catalyst, among all others, could provide the largest yield of 1,3-PDO (above 99.0%) and highest TOF (4.70 × 103 S−1). The optimized reaction conditions over the Ru–40Ni/SiO2 catalyst had been established as follows: reaction temperature = 80 °C, H2 pressure = 2.0 MPa and LHSV = 0.4 h−1. In consideration of its extremely low H2 pressure and very high yield of 1,3-PDO for the hydrogenation of 3-HPA, to the best of our knowledge, the Ru–40Ni/SiO2 catalyst appeared to be the most efficient catalyst among all others reported in the literature. The good performance enabled the Ru–40Ni/SiO2 catalyst to be very promising in its industrial application.