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Acidity plays a vital role in methane conversion by co-feeding method, which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane. In this work, Zn, Ni, Mo, La, Ga, Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane. It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction. Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%, whose aromatic selectivity increases from 27.2% to 52.2% compared with that of HZSM-5. Besides, the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics (MTA) reaction.

In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of AlMe3 and phenols were synthesized, which could serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization. The molar ratios of [PhOH]/[AlMe3] and [H2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe3] = 0.5 and [H2O]/[Al] = 0.7. Various aluminoxanes with different [―OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems (> 30 wt%). This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.

In the refinery, purifiers are widely used in the recovery of hydrogen components of the emissions from hydrogen consumption units. Hydrogen network containing purification units have been optimized and integrated by lots of researchers. However, purifier models such as PSA, membrane separation have nonlinear characteristics. Even if minimizing hydrogen utility, mathematical programming models adopted by most of the researchers belong to the non-convex and nonlinear models, not guaranteeing global optimal solution. On the basis of previous studies, this paper proposes a mixed integer linear programming model to obtain a minimum hydrogen utility consumption. This method can get the inlet flowrate simultaneously. Case studies indicate that this method is effective for both hydrogen and water networks.

Numerical simulations based on the Eulerian-Eulerian approach have been performed in the study of interphase heat transfer in a gas solid fluidized bed. The kinetic theory of granular flow (KTGF) has been used to describe the solid phase rheology. An assessment of drag models in the prediction of heat transfer coefficients shows that no major difference is observed in the choice of the drag model used. Fluctuations of the interphase heat transfer coefficient have been found to be closely related to the bubble motion in the bed. Effects of the wall boundary condition, inlet gas velocity, initial bed height and particle size on the predicted heat transfer coefficient have also been investigated. Typical temperature profiles in the bed show that thermal saturation is attained instantaneously close to the gas distributor. Simulated results of the coefficients are in fair agreement with those reported in literature.

To satisfy fast changing market demands, polymer plants are forced to operate under frequent grade transition polices which produce a huge amount of off-specification product and waste the time of normal production. In the present study, a model of grade transition is presented for the industrial continuous high-density polyethylene (HDPE) slurry process, which includes two stirred reactors connected in either parallel mode or series mode. The objective of the study is to maximize the economic benefit and minimize the negative environmental impact of the process. Different objective functions are constructed according to the different operation modes. The trajectories of the operating variables can be optimized successfully with the desired polymer quality targets. A heuristic combined strategy is proposed to solve the unstable problem caused by mathematical optimization during the transition between parallel mode and series mode. The problem is solved from three aspects: temperature, operating variables, and material flow. The result indicates that the heuristic combined grade transition takes longer time, but is more feasible in the restriction of the manipulated variables and therefore more effective in controlling the instantaneous properties of the polymer produced.

An energy distribution theory was presented based on regular evolvement of energy fraction of acoustic signals with fluidization velocity. Wavelet packet analysis was used in processing the acoustic signals originated from particle impact on the wall of a fluidized bed. A new criterion of judging incipient fluidization (U mf) velocity and minimum turbulent velocity (U mt) was proposed according to the energy distribution theory. Experiments were performed with five groups of high density polyethylene (PE) particles and one bimodal PE to acquire incipient fluidization velocity and minimum turbulent velocity by using the criterion. The feasibility of this method in obtaining characteristic fluidization parameters was further verified by comparing it to results from the pressure drop method and the empirical value from industry.