Beijing Institute of Petrochemical Technology

About: Beijing Institute of Petrochemical Technology is a education organization based out in Beijing, China. It is known for research contribution in the topics: Catalysis & Corrosion. The organization has 2468 authors who have published 1937 publications receiving 19270 citations.

Relationship between microstructure and dielectric property of hydroxyl-terminated butadiene–acrylonitrile copolymer-based polyurethanes

Abstract: Exploring novel dielectric polymer materials with high dielectric performance would play a crucial role in the high energy density capacitor applications. In this work, novel polyurethanes (PUs) for high dielectric performance were fabricated using containing polar nitrile group (–C ≡ N) of hydroxyl-terminated polybutadiene–acrylonitrile copolymer (HTBN) as soft segment and the hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI) as hard segment component. Effect of diisocyanate chemical structure on microphase separation, crystallization, dielectric property and mechanical properties of HTBN-based PUs, and the relationship between structure and dielectric property of HTBN-based PUs were investigated. The HTBN-based PUs showed high dielectric constant (>6.4) and low dissipation factor (<0.077) at the frequency range from 1 to 106 Hz. The crystallinity, degree of microphase separation and dielectric constant of HDI-/HTBN-based PU showed higher than that of MDI/HTBN and TDI-/HTBN-based PUs. Our results indicated that the dielectric constant and dissipation factor of PUs are not only dependent on the dipole orientation of hard and soft segments, but also strongly dependent on their microstructure including degree of microphase separation and crystallinity.

Development of a VOF+LS+SPP method based on FLUENT for simulating bubble behaviors in the electric field

Abstract: To simulate bubble dynamic behaviors under an electric field conveniently and accurately, a volume-of-fluid, level set, and smoothed physical parameter (VOF+LS+SPP) method based on FLUENT is first ...

Niobium phosphotungstates: excellent solid acid catalysts for the dehydration of fructose to 5-hydroxymethylfurfural under mild conditions

Abstract: The efficient conversion of carbohydrates to 5-hydroxymethylfurfural (5-HMF) under mild conditions represents a very attractive and promising method of producing important building blocks. In this work, niobium phosphotungstates, with Nb/P molar ratios of 0.6, 1.0, 2.0 and 4.0 (NbPW-06, NbPW-1, NbPW-2, and NbPW-4, respectively) have been prepared by a facile, one-pot, alcohol-mediated thermal process and used for the direct conversion of fructose to 5-HMF. By adding a certain amount of Nb, the surface of the catalyst became enriched in P, and this enrichment was associated with the presence of surface P–OH groups that offered Bronsted acid sites that can activate superficial hydrogen species to facilitate 5-HMF generation. Pyridine-FTIR confirmed the presence of Bronsted and Lewis acid sites, which might play important roles in the dehydration of fructose to 5-HMF. Furthermore, polar aprotic solvents were well-suited for the conversion, and higher yields of 5-HMF were obtained in polar aprotic solvents than in nonpolar solvents. A 5-HMF yield of 96.7% with complete fructose consumption was obtained over NbPW-06 in DMSO at 80 °C after 90 min. In addition, NbPW-06 could be recycled several times without a significant decrease in the catalytic activity. A catalytic mechanism for this reaction was proposed. Moreover, this catalytic system can also be utilized for the dehydration of sucrose and inulin to 5-HMF in satisfactory yields. This study establishes an important platform for the further design of Nb-containing catalysts for the production of 5-HMF from carbohydrates under mild conditions.