Haibo Jin

The Effect of Sparger Geometry on Gas Bubble Flow Behaviors Using Electrical Resistance Tomography

Abstract By electrical resistance tomography (ERT) the cross sectional profiles of gas hold-up in a o56mm bubble column are obtained with four designs of gas sparger. The effect of sparger geometry on the bubble distribution is revealed by applying a sensitivity conjugated gradients reconstruction method (SCG). Experimental results show that overall hold-up obtained by ERT is generally in good agreement with those measured with the pressure transducer and the ERT system produces informative evidence that the radial profiles of hold-up is very similar to the sparger design in the lower section of bubble column. Meanwhile, the rise velocity of bubble swarm and the Sauter mean bubble size are evaluated using ERT based on dynamic gas disengagement theory. The experimental results are in good agreement with correlations and conventional estimation obtained using pressure transmitter methods.

Synthesis and characterization of a K/K2CO3-based solid superbase as a catalyst in propylene dimerization

A novel solid superbase 3%K/K2CO3 was prepared by loading metallic potassium on K2CO3. The optimized preparation conditions included a loading time of 1.5 h, loading temperature of 150 °C, loading amount of 3wt% and average carrier size of 120 μm. Under the optimum conditions, the conversion of propylene is about 60% with the selectivity of dimers 98.5% and the selectivity of 4MP1 86.3%. In addition, the superbase 3%K/K2CO3 has a base strength of H−≥37, and the concentration of basic sites of H−≥35 is approximately 0.3mmol·gCAT−1. The microcrystal of metallic potassium was determined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was assumed that the oxygen species, which are adjacent to lattice defects, such as the crystalline corners, edges and vacancies of metallic potassium micro-crystals, constituted the superbasic sites.

Measurement of Gas Holdup Profiles in A Gas Liquid Cocurrent Bubble Column Using Electrical Resistance Tomography

Radial variation of the gas holdup and mean holdups were investigated in 0.160m i.d. bubble column using electrical resistance tomography with two axial locations (Plane 1 and Plane 2). In all the experiments tap water was liquid phase and air was gas phase. Superficial gas velocity was varied from 0.02 to 0.25 m/s, and the liquid velocity varied from 0 to 0.01 m/s. The effect of liquid velocity on the mean holdups and radial gas holdup distribution was discussed. The experimental results showed the liquid velocity influence slightly the mean holdup and radial hold‐ups distribution in the operating condition, and the liquid flow can improve the trasition gas velocity for homogeneous regime to heterogeneous regime. Meanwhile the average column gas holdups as a function of gas velocity derived from differential pressure method and electrical resistance tomography method. The agreement between results obtained by two methods is generally very good in homogeneous regime. But in transition regime and heterogen...

Green synthesis of acetaldehyde oxime using ammonia oxidation in the TS-1/H2O2 system

A qualitative analysis for the ammoximation of acetaldehyde to its oxime using TS-1 as a catalyst and H2O2 as an oxidant was investigated. According to the hydroxylamine mechanism, the effects of temperature, H2O2/acetaldehyde, NH3/acetaldehyde, and the amount of TS-1 on the catalytic properties of TS-1 were studied in detail. The results showed that temperature determined the main and side reactions, and ammonia provided an alkaline environment. Under the optimized reaction conditions, acetaldehyde conversion and acetaldehyde oxime selectivity could reach up to 89.5 and 82.7%, respectively. The comprehensive results of FTIR, XRD, BET and XRF declared that TS-1 deactivation was caused by carbon deposition, not structural damage. The catalyst could be regenerated by calcination when the temperature exceeded a certain minimum value. Meanwhile, the reaction mechanism shows that the procedure of generating hydroxylamine was the control step of reaction, and the entire reaction goes on the route of hydroxylamine.

The catalytic characteristic and synthesis technique for 4-methyl-1-pentene over a potassium-supported superbase catalyst

Abstract The dimerization of propene to 4-methyl-1-pentene (4MP1) was studied in a fixed-bed reactor at 150 °C temperature, 8 MPa pressure, and 1 h−1 liquid hourly space velocity (LHSV) in the presence of solid superbase with 20 wt% one-pass conversion to hexene and 88% selectivity toward 4MP1. Based on the reaction results, propene competes with 4MP1 for adsorption on the catalyst surface. A higher reaction pressure or a lower liquid rate of 4MP1, controlled by a suitable propene LHSV or reaction temperature, was beneficial to the adsorption of propene, which reduced the isomerization of 4MP1. Under optimized conditions, propene dimerization was stable for 200 h, and isomerization was limited to less than 5%, yielding products with about 19% one-pass conversion to hexene by weight and 87% selectivity toward 4MP1.

Measurement of hydrodynamic parameters in multi-stage bubble column using electrical resistance tomography techniques

Based on the principle of CSTRs in series, hydrodynamic parameters of bubble column embedded with sieve plates are studied. The measurements were performed with superficial gas velocities in the range 0.026-0.156 m/s and studies in bubble columns of diameter D=0.282m with the air-water system are carried out. The gas holdup(eg) and its radial distribution above and under the plates of the bubble column are measured using Electrical Resistance Tomography (ERT) and the differential pressure method. The effects of sieve plates with different fractional hole areas and different hole diameters on gas holdup are discussed. The experimental result shows a good agreement with the ones using differential pressure method and the ERT, and the different sieve plates have different effect on the hydrodynamic parameter of the multi-stage bubble column. With the gas superficial velocity added, the local gas holdup increased. Moreover, the gas holdup D-value of dual-planes is increased with a decrease of the percent free...