Haibin Jiang

Polymer-supported catalysts for clean preparation of n-butanol

A new type of RANEY® metal catalyst supported by polymer was developed for the clean preparation of n-butanol. Unlike traditional supported catalysts, the newly developed alkalescent polyamide 6 (PA6) supported RANEY® nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry. The significantly enhanced catalyst selectivity of the polymer-supported RANEY® metal catalyst was attributed to the elimination of the acid-catalyzed side reaction associated with RANEY® metals and traditional catalyst supports, such as Al2O3 and SiO2. By eliminating acid-catalyzed side reactions, therefore, green chemistry could be achieved through reducing resources and energy consumption in chemical reactions. Furthermore, the preparation and recycling of the polymer-supported catalysts are also much more eco-friendly than for traditional Al2O3-/SiO2-supported catalysts. The methodology developed in this study to use alkalescent polymers as the catalyst support could be applied to the whole catalyst family, including a series of important RANEY® metal catalysts (e.g., RANEY® nickel, RANEY® cobalt, RANEY® copper) used routinely in the chemical industry.

Different influences of nucleating agents on crystallization behavior of polyethylene and polypropylene

The crystallization behavior of polyethylene (PE) and polypropylene (PP), including the neat ones and the ones nucleated with the same nucleating agent (NA), was studied by DSC. It was found that the nucleating agent decelerated the PE nonisothermal crystallization process. NA did enhance the nucleating rates for both PE and PP, but the linear growth rate dominated the volumetric growth rate for PE, and the volumetric growth rate dominated the overall crystallization rate. That is why PE nucleated with NA had a slower overall crystallization rate than the neat one.

Effect of polyamide on selectivity of its supported Raney Ni catalyst

A newly-developed polyamide supported Raney Ni catalyst, which is suitable for use in fix-bed reactions with high selectivity, was studied in this paper. Selective hydrogenation of acetone to isopropanol was chosen as a probe reaction. It has been found that clean preparation of isopropanol could be achieved, that is to say, the two main byproducts (isopropyl ether and methyl- iso-butyl carbinol) could be eliminated with the newly-developed polyamide supported Raney Ni catalyst. The elimination of these side reactions was attributed to the adsorption effect of polyamide support and a model was proposed. The proposed model was further proved by hydroamination reaction of acetone. According to this model, catalyst support can play an important role in chemical reactions. Different products could be produced when different catalyst support is used, the main reaction and side reactions can even be reversed sometimes when the chemicals, active component of catalyst and reaction condition are the same. This model could help to improve catalytic selectivity of many Raney metal catalysts used routinely in chemical and oil refining industry, and is also useful for hydrogenation reactions in pharmaceutical and food industry.

Polymer-Supported Raney Nickel Catalysts for Sustainable Reduction Reactions

Green is the future of chemistry. Catalysts with high selectivity are the key to green chemistry. Polymer-supported Raney catalysts have been found to have outstanding performance in the clean preparation of some chemicals. For example, a polyamide 6-supported Raney nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry, and eliminated the two main byproducts (isopropyl ether and methyl-iso-butylcarbinol) in the hydrogenation of acetone to isopropanol. Meanwhile, a model for how the polymer support brought about the elimination of byproducts is proposed and confirmed. In this account the preparation and applications of polymer-supported Raney catalysts along with the corresponding models will be reviewed.

Conductive Graphene–Melamine Sponge Prepared via Microwave Irradiation

A conductive graphene-melamine sponge (MS) prepared via microwave irradiation is reported in this paper. Graphene oxide supported on the MS was prereduced first at 100 °C and then further reduced in a household microwave oven at over 1000 °C. It was surprising to find that graphene oxide on the MS was reduced perfectly while the three-dimensional structure of the MS was kept well after high-temperature reduction via microwave irradiation. Slight pyrolysis of MS was also found during 5 s microwave irradiation, resulting in nitrogen generation from the pyrolysis of the MS being doped into graphene, which could benefit the electric conductivity of the prepared graphene-MS. The electric conductivity of the prepared graphene-MS is about 0.12-1.0 S/m because of the high reduction degree of graphene oxide and nitrogen doping. On the other hand, different from the pure MS, the newly developed conductive graphene-MS possesses superhydrophobic and superoleophilic properties. Overall, the newly developed conductive graphene-MS contained 94.3 wt % MS and 5.7 wt % N-doped graphene and is a cost-effective material with good elasticity, high conductivity, superhydrophobicity, and superoleophilicity.

Preparation and application of N-doped carbon nanotube arrays on graphene fibers

A new kind of carbon hybrid material with a unique structure and outstanding mechanical and functional properties is reported in this article. Nitrogen-doped carbon nanotube (CNT) arrays with inside located Ni particles are in situ grown on the surface of phenolic carbon modified graphene fibers during their conversion from graphene oxide fibers. The carbon hybrid fibers exhibit not only high tensile strength and elongation at the break, but also excellent flexibility since the CNT arrays cover all the surface of the highly strong graphene fiber. This well-constructed carbon material would be suitable for catalysts, polymer composites, hydrogen storage, oxygen reduction reaction etc.