Minghan Han

Preparation of biodiesel from waste oils catalyzed by a Brønsted acidic ionic liquid.

Preparation of biodiesel from waste oils catalyzed by a novel Brønsted acidic ionic liquid with an alkane sulfonic acid group was investigated. The acidity and the activity of the ionic liquid were very low at lower temperature when the ionic liquid was crystalloid; they recovered at higher temperature when the crystallized ionic liquid was liquefied. When methanol:oils:catalyst molar ratios were 12:1:0.06, the yield of fatty acid methyl esters can reach 93.5% after the reaction of acidic oil with methanol had taken place at 170 degrees C for 4h. In addition, the ionic liquid had a good reusability and can be easily separated from the biodiesel by simple decantation.

Alkylation of Benzene with Long-Chain Olefins Catalyzed by Fluorinated β Zeolite

The effects of fluorination on Hβ zeolite and alkylation of benzene with long-chain olefins catalyzed by fluorinated β zeolite are investigated. The lifetime of the catalysts depends on the surface area and pore volume rather than acidity. When the fluorine content is 0.5%, the lifetime improves by 30%, when the catalyst has maximum specific surface area and pore volume.

Study on a catalytic distillation column with a novel internal

A novel internal for holding a catalyst in a catalytic distillation column was studied and its feasibility was verified by a model reaction, which is the alkylation of benzene with propylene over Hβ zeolite catalyst. The novel internal enlarges the void of the catalyst bed and provides the gas and liquid flow channels. It was proved that the catalytic distillation column with the novel internal has such advantages as simple structure, low operating cost, convenience for loading and unloading catalyst, and large catalyst loading fraction. It was found that the operational capability of the column with the novel internal whose volume fraction is about 30% is similar to that of a column filled with catalysts mixed with Cannon rings whose volume fraction is about 80%. It was also found that compared with the fixed-bed bubble reactor, the selectivity of cumene and the conversion of benzene are significantly improved in the CD (Catalytic Distillation) column with the internal.

Pressure drop for two phase counter-current flow in a packed column with a novel internal

Abstract A novel internal made of several structured porous passages can eliminate excessive pressure drop and “flooding” in a packed column with conventional gas liquid counter-current flow. A pressure drop model is developed on the assumption that the internal part divides the gas flow into two branches, one of which contacts the liquid in a conventional counter-current flow and the other in a new cross current flow. The model shows that the gas velocity for counter-current flow in a column with these internal parts of 15–30% volume fraction is about 5–30% of that without the internal parts and more gas flows in the cross current pattern. Decreases in the gas velocity and liquid hold-up make the pressure drop low.

Characteristics of the reactive distillation column with a novel internal

Abstract A new catalyst loading method, in which catalyst particles are packed in a reactor with a novel internal, has been studied by measuring pressure drop, RTD, liquid holdup and mass transfer. It can be inferred from experimental results that the internal changes the conventional gas and liquid counter-current flow into a new cross-current flow, so the problems of excessive pressure drop and “flooding” are avoided. When pressure drop, liquid holdup, RTD and mass transfer coefficient are similar, the catalyst loading fraction of the new method is much higher than that of conventional methods. Furthermore, the reactive distillation reactor with the novel internal has advantages such as simple structure, low operating cost, and convenience for installation and removal of the catalyst.

Stability improvement of the Nieuwland catalyst in the dimerization of acetylene to monovinylacetylene

Abstract In the process of dimerization of acetylene to produce monovinylacetylene (MVA), the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated. The formula of the precipitate was CuCl·2C 2 H 2 ·1/5NH 3 , and it was presumed to be formed by the combination of NH 3 , C 2 H 2 and [Cu]-acetylene p -complex, which was an intermediate in the dimerization reaction. The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate, whereas excessive H + is unfavorable to the dimerization reaction of acetylene. To balance between high acetylene conversion and low loss rate of CuCl, the optimum mass percentage of HCl in the added hydrochloric acid was determined. The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h −1 to 360 h −1 . The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80–5.97 during the reaction process, which was good for both catalyst life and acetylene conversion.

Self-diffusion in a fluid of square-well spheres

The self-diffusion coefficients for a dense fluid of particles interacting with a square-well potential are described. The expression for self-diffusion coefficients obtained by the Chapman–Enskog method of solution is corrected by the molecular dynamics simulation data. The structural data for the square-well fluid required in the calculation are obtained from explicit analytic equations for the radial distribution function. The corrected equation represents the self-diffusion coefficients with an average absolute deviation of 4.63% for the square-well fluid. The results are compared with those of other expressions. In addition, the self-diffusion coefficients for real fluids composed of simple, near spherical molecules are correlated using the square-well potential, and acceptable agreement is obtained between the calculated and experimental diffusion data.

REACTOR MODELING OF AN INNOVATIVE LIQUID-SOLID CIRCULATING MOVING BED FOR THE SYNTHESIS OF LINEAR ALKYL BENZENES

The circulating moving bed is an innovative coupled reactor for producing linear alkyl benzenes. It can be used with shorter life span catalysts compared to traditional fixed bed reactors. A model is developed in which the effect of catalyst deactivation on the reaction is simulated using infinitesimal balance equations. The results of step changes between steady states and unsteady states have been calculated with the model.

Particle transport by jet pump in a new liquid-solid circulating moving bed reactor

Abstract The liquid–solid circulating moving bed reactor is a novel one, which consists of two or more reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through an upper conduit and to the particle transport system through a lower conduit, and then are conveyed into the upper reaction chamber through a riser. The renewing speed of particles in the reaction chamber is determined by the circulating rate of particles, which is one of the key factors in the operation of the reactor. Three different kinds of auxiliary liquids are used to regulate the circulating rate of particles, and a suitable configuration of particle transport system is established. A model of particle transport based on mass, momentum and energy balance is proposed and used for simulation of the process.

Effect of solvent on catalytic performance of anhydrous catalyst in acetylene dimerization to monovinylacetylene

Abstract The production of monovinylacetylene (MVA) through Cu(I)-catalyzed acetylene dimerization reaction was performed in different reaction media. Based on the analyses of crystals precipitated from the catalyst solution and UV-Vis spectra of the catalysts, the reaction mechanism and solvent dependence were studied. The highest yield of MVA can be obtained when dimethylformamide is used as solvent because of its strong coordination ability to Cu(I). The activation of C≡C bond is presumed to be improved when the catalytic metal ion is coordinated by a solvent with less steric hindrance and electron-rich coordination atom. The results of the present study provide a possible way to accelerate the metal-catalyzed homogeneous reaction of alkyne substrates through careful selection of a solvent.