A Comparative Study on Heat Transfer Performance of Typical Petrochemical Reactors

The performance of heat transfer is a key issue for reactor design in petrochemical industry. Since the heat transfer in reactors is a complicated process and depends on multiple parameters, the evaluation of the heat transfer performance is usually challenging, and few previous studies gave an overall view of heat exchange performance of different types of reactors. In this review, heat transfer coefficients of two types of petrochemical reactors, including the packed bed and the fluidized bed, were systematically analyzed and compared based on a number of reported correlations. The relationship between heat transfer coefficients and fluid flow velocity in different reactors has been well established, which clearly demonstrates the varying range of their heat transfer coefficients. Heat transfer coefficients of gas-phase packed bed can exceed 200 W/m^2·K, rather than the suggested values(17—89 W/m^2·K) mentioned in the literature. The fluidized bed shows better performance for both two-phase and three-phase beds as compared to the packed bed. Systems with liquid phase also show better heat transfer performance than other phases because of the larger heat capacity of liquid. Thus the industrial three-phase fluidized beds have the best heat transfer performance with an overall heat transfer coefficient of greater than 1 000 W/m^2·K. The heat transfer results provided by this review can afford not only new insights into the heat transfer in typical reactors, but also the basis and guidelines for reactor design and selection.

The optimum conditions for methanol conversion to dimethyl ether over modified sulfated zirconia catalysts prepared by different methods

Sulfated zirconia(SZ)and two promoted 1% Mn/SZ catalysts which have been prepared via sol gel(Mn/SZ-S)and impregnation(Mn/SZ-I)methods were studied.The morphology of the catalysts was characterized by XRD,BET,NH3-TPD,ICP,SEM and FT-IR analysis.The conversion of methanol to dimethyl ether and hydrocarbons was carried out in the temperature range of 120−300℃.The Mn/SZ-S showed the highest activity due to the high surface area with suitable acidity.The optimum condition of Mn/SZ-S catalyst was investigated at 200℃ and LHSV of 0.02 h^−1 in a time range from 30 to 210 min.It was found that the total conversion decreased from 80.18% to 53.26% at 210 min.The reusability of this catalyst was studied at the optimum condition up till four cycles for 1 h.The characterization of the reused catalyst showed a significant change in the structure and surface acidity due to the blockage of the surface acid sited by carbonaceous materials.

Application of PIMS Software in Monthly Planning of Refinery Production

This article describes the application of the PIMS software in formulating monthly refining production plan. Application of the PIMS software can help to solve a series of problems related with monthly plan of refining production such as optimized selection of crude and feedstocks, optimized selection of production scale and processing scheme, identification of bottlenecks and their mitigation,optimized selection of turnaround time and optimized selection of operating regime, which have increased the economic benefits of refining enterprises. With the further development and improvement of models the PIMS software will play an increasingly important role in formulating monthly plans of refining operations and production management at refineries. This article also explores the problems existing in refinery monthly planning, and has made recommendations on developing and improving models and reporting system, enhancement of basic data acquisition, model maintenance personnel and staff training.

Prospect for Upgrading China's Gasoline Consumption

China’s economy has maintained a steady and rapid development, the growth rate of automobiles and gasoline output and sales volume is far beyond the national economic growth rate over the same period, and much higher than that in developed countries. According

Post-synthetic metalation of organic cage for enhanced porosity and catalytic performance

Porous organic cages(POCs)have shown great potential in many applications,and post-synthetic modification(PSM)has been confirmed to be an effective strategy to tailor their structures and related functionalities.However,it is extremely challenging to develop a general platform for simple-to-make functional POCs for advanced applications by PSM method.Herein,we reported that octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage(HPOC-401)provides an excellent platform for post-synthetic metalation by various transition metal(TM)ions under mild conditions due to the abundance of coordination sites in its skeleton.Such metalated products(HPOC-401-TM)exhibit Brunauer-Emmett-Teller(BET)surface area up to1,456 m^(2)g^(-1),much higher than that of the pristine HPOC-401,which has a BET value of 474 m^(2)g^(-1).Moreover,the metalation and porosity increases further influence their gas capture,separation,as well as catalytic performance.For instance,HPOC-401-TM products exhibit higher CO_(2),H_(2),and C2 hydrocarbon gas uptake,as well as higher C_(2)H_(6)/C_(2)H_(4) selectivity than HPOC-401.Moreover,the HPOC-401-TM also shows better catalytic performance in the cycloaddition of CO_(2) with epoxides compared to HPOC-401.These findings uncover a simple yet effective approach for modifying the porosity characteristics of organic cages,which will undoubtedly expand their future implementations.

Use of breakthrough experiment to evaluate the performance of hydrogen isotope separation for metal-organic frameworks M-MOF-74(M=Co, Ni, Mg, Zn)

The unique adsorption performance of metal-organic frameworks(MOFs) indicates a new direction for gas separation and purification. The low-temperature distillation, as a traditional technique for hydrogen isotope separation, is limited as it is a high energy-and cost-intensive process. Instead of utilizing such a conventional separation route, we use ordered microporous frameworks based on a physical adsorption mechanism to solve the challenge of hydrogen isotope separation. Herein we analyze M-MOF-74(M=Co, Ni, Mg, Zn), featuring a hexagonal channel about 11 ? and high density of open metal sites, for their ability to separate and purify deuterium from the hydrogen isotope mixture by dynamic column breakthrough experiments. Our results show that the combination of the strength of binding sites, density of coordinatively unsaturated metal sites and hydrogen isotope adsorption capacity of materials renders Co-MOF-74 as an optimal adsorbent for the capture of deuterium from hydrogen isotope mixtures in a simulated industrial process.

Tunable Cage-Based Three- Dimensional Covalent Organic Frameworks

It is extremely challenging to construct three-dimensional(3D)crystalline covalent organic frameworks(COFs)with flexible building blocks and to further explore their tunable or adaptive characteristics due to crystallization and structure determination difficulties.Herein,we constructed three crystalline isostructural 3D-OC-COFs based on a newly synthesized flexible organic cage(6NH_(2)-OC.4HCl)through a novel in situ acid–base neutralization strategy.

The competitive and synergistic effect between adsorption enthalpy and capacity in D_(2)/H_(2)separation of M_(2)(m-dobdc)frameworks

Hydrogen isotope separation is a challenging task due to their similar properties.Herein,based on the chemical affinity quantum sieve(CAQS)effect,the D_(2)/H_(2)separation performance of M_(2)(m-dobdc)(M=Co,Ni,Mg,Mn;m-dobdc^(4-)=4,6-dioxido-1,3-benzenedicarboxylate),a series of honeycomb-shaped MOFs with high stability and abundant open metal sites,are studied by gases sorption and breakthrough experiments,in which two critical factors,gas uptake and adsorption enthalpy,are taken into consideration.Among these MOFs,Co_(2)(m-dobdc)exhibits the longest D_(2)retention time of 180 min/g(H_(2)/D_(2)/Ne:1/1/98)at 77 K because of its second-highest adsorption enthalpy(10.7 kJ/mol for H_(2)and 11.8 kJ/mol for D_(2))and the best sorption capacity(5.22 mmol/g for H_(2)and 5.49 mmol/g for D_(2))under low pressure of 1 kPa and 77 K,which make it a promising material for industrial hydrogen isotope separation.Moreover,the results indicate that H_(2)and D_(2)capacities under low pressure(about 1 kPa)dominate the final D_(2)/H_(2)separation property of MOFs.