257 publications from this institution
Abstract A highly efficient and simple route for the synthesis of 2-substituted benzo[b]furans has been developed by palladium-catalyzed cross-coupling reaction of 2-halobenzo[b]furans with aryl, alkynyl, and alkylaluminum reagents. Various 2-aryl-, 2-alkynyl-, and 2-alkyl-substituted benzo[b]furan derivatives can be obtained in 23–97% isolated yields using 2–3 mol% PdCl2/4–6 mol% XantPhos as the catalyst under mild reaction conditions. The aryls bearing electron-donating or electron-withdrawing groups in 2-halobenzo[b]furans gave products in 40–97% isolated yields. In addition, aluminum reagents containing thienyl, furanyl, trimethylsilanyl, and benzyl groups worked efficiently with 2-halobenzo[b]furans as well, and three bioactive molecules with 2-substituted benzo[b]furan skeleton were synthesized. Furthermore, the broad substrates scope and the typical maintenance of vigorous efficiency on gram scale make this protocol a potentially practical method to synthesize 2-substituted benzo[b]furan derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.
In this study, the flash carbonization data obtained from reactor at Morgantown Energy Technology Center (METC) are analyzed to develop rate expressions. The heat transfer characteristics and hydrodynamics of the carbonizer have been simulated. The result indicates that the solid particle temperature is controlled by the radiation during the period immediately after coal particles are fed into the reactor. The temperature of the gas at the region subsequent to the entry region is controlled by the convection between the solids and the gas. Both the solid temperature and the gas temperature seem to increase rapidly due to the radiation from the reactor wall which has high temperature. In regard to the rate expression for coal carbonization, the rate equation based on Wen et al. fit the data better than that based on Badzioch and Hawksley. However, neither expression predicts the effect of pressure since both of them are derived based on the atmospheric condition. In addition two rate expressions were formulated to account for the pressure effect and were tested against the data from METC as well as against two other sets of published data. The results indicated that these expressions could predict the trends of the data, but theremore » were still discrepancies from the experimental data. Hence more accurate data taken under better controlled operating conditions are necessary in order to develop a better rate expression for flash carbonization of coal. 16 references, 18 figures, 7 tables.« less
Prior to optimization of methanation processes, heat exchanger optimization is performed; computer simulation of methanation process is then programmed based on kinetic information, cost information and heat and material balance; suitable techniques of optimization of methanation processes are selected and optimum conditions and designs of a various systems are found; various systems of catalytic fixed bed reactors are considered - adiabatic system, heat extraction system, cold quench system and recycle system; size of plant was for production of 250 x 10/sup 9/ Btu/day of pipe line gas. 17 references.
The high-temperature TGA has been operated with steam and CO/sub 2/ for lignite and bituminous chars. Problems with temperature calibration require verification of results before further analysis. Work on attrition of coal in a pressurized, sand fluid-bed was completed. Conditions were 5-45 cm/sec at 1 to 7 atm total pressure. The rate obtained increases with fluidizing velocity and pressure. The rate constants are negligible at velocities below approx. = 30 cm/sec for particles 60 to 175 ..mu.. in diameter. Results appear to be dependent on change in hydrodynamics with pressure. A hot-bed fluidization system was commissioned and operated. Entrainment/elutriation data for coal particles was obtained in the range 5 to 90 cm/sec at 800 to 900/sup 0/C for a 12.7 cm sand bed.
The development of acid-sensitive OER (Oxygen Evolution Reaction) electrocatalysts based on ruthenium oxides is a crucial step toward achieving large-scale hydrogen production in low-cost Proton Exchange Membrane (PEM) electrolyzers. However, a major challenge in this field is to overcome the tendency of ruthenium-based metal oxides to dissolve in acidic environments, which affects their long-term stability. In this study, we employed MIL-101(Cr) as a precursor and used a simple room-temperature stirring and annealing process to prepare ternary spinel metal oxides Cr0.5CoxRu0.5-xO2-δ. Detailed physical characterization, combined with electrochemical tests, demonstrated that the introduction of cobalt (Co) reduces the volume of individual catalyst crystallites without disrupting the spinel crystal structure and inherent activity of CrO2-RuO2. Simultaneously, the Co and Cr doping lowers the oxidation state of ruthenium (Ru) within the catalyst system. Lower oxidation states of Ru are more stable during the OER reaction, ensuring the stability of this catalyst to at least 25 hours. Furthermore, Co incorporation raises the energy required for oxygen vacancy formation, reduces the involvement of lattice oxygen, and enhances the catalyst's activity. The best catalyst Cr0.5Co0.17Ru0.33O2-δ exhibits the overpotential of only 224 mV at 10 mA cm−2 in 0.5 M H2SO4. This study offers a viable strategy for developing highly active and stable catalysts in acidic media by controlling the electronic structure of RuO2.
