Volume 19, Issue 4

As a significant component of catalyst system, catalyst carrier can impact on coating amount of active component, and in turn catalytic activity. In this work, study of bamboo-based activated carbon as the catalyst carrier for gas phase synthesis of vinyl acetate from acetylene and acetic acid was carried out. Characterization and experimental results showed that bamboo-based activated carbon possessed the conditions and potential of being a catalyst carrier and characterized a greater advantage in structure and properties after modification. After ultrasonic treatment, it was found that the mesoporous distribution of activated carbon increased, which promoted the adsorption to zinc acetate and resulted in 23% increase in productivity of catalyst. Simultaneously, it had a different effect on surface area and pore-size distribution of activated carbon by thermal treatment at high temperatures in N 2 and CO 2 atmosphere. The productivity of catalyst with bamboo-based activated carbon as catalyst carrier after thermal treatment in N 2 and CO 2 can be increased by 14 and 20%, respectively. Furthermore, based on the influence of pore size on adsorption and reaction of active components, the necessity of expanding pores of carbon was explained in this paper, which pointed out the direction of activated carbon modification.

Non-ideal mixing phenomena are widely found in industrial chemical reactors. In this work we derived the bifurcation formulas for a non-adiabatic CSTR with an irreversible exothermic first order reaction with the non-ideal mixing effect. This is investigated via dynamic behavior simulations based on Chollete’s model. The results show that the non-ideal mixing parameter n (the fraction of the feed entering the perfect mixing zone) determines the variation between six classified regions and dominates the dynamic behavior patterns in the steady-state response diagram. On the other hand, the phase portraits of examples verify the formulas derived in this work. We note that the non-ideal mixing effect has significant importance in CSTR design and control steps. For example, in the safe operating region for an ideal mixing CSTR, non-linear dynamics are obtained by the system under non-ideal mixing conditions ( n  ≠ 1). The present study has significance and help for chemical reactor design and CSTR control.

This work aims to investigate the radical mechanism responsible for the degradation of a highly soluble pollutant in water. The AG25 dye was chosen as substrate and the GAD-Spray as biphasic reactor to treat it remotely. The study is conducted through experiments and simulations using Comsol Multiphysics-chemical engineering module. The Hydrodynamics coupled with the plasma-reaction has demonstrated that a low mass transfer in the droplet favorites the removal of the pollutant. It indicates that the plasma-reactions take place at the stagnant liquid film are far from the bulk of the droplet. Numerical modeling fitted by the conversion rate of the reagent has shown that the peroxynitrous acid HOONO (PON) is responsible for the degradation of AG25 in water. Consequently, and according different kinetic mechanisms, a radical mechanism has been predicted based on this deduction. The removal and the degradation rates were of 88 and 83% respectively during 90 min after the plasma exposure. The results of simulations showed a significant agreement between the calculated and the real removal rate of AG25. Through this study, it can be confirmed that GAD-spray-tower plasma reactor is efficient to eliminate and degrade remotely a very soluble pollutant through the HOONO (PON) plasma long-lived species.

It is being considered to pyrolyze lignin-rich biomass samples (hazelnut shells, HSs) into bio-fuels and chemicals to solve energy shortages and environmental concerns, volatile products (including liquid products and gas products) were produced and characterized from HSs pyrolysis at 400–1000 °C. With the temperature increases, the maximum output of liquid products was up to 35.79% produced at 700 °C, gas products yields increased from 21.82 to 55.46%. Gas chromatography and mass spectrometry (GC–MS) study indicated that liquid products from HSs riched in phenolic compounds, exceed 42% of liquid products and increased as the temperature rises. The application experiment showed that HSs liquid products had a significant role in antioxidant activity, and revealed that not limited to phenols, all compounds containing phenolic hydroxyl structure act as antioxidant. Composition analysis of gas products showed that more combustible gases were produced at the higher temperature, resulted in the significant increase in gas products higher heating value (HHV) from 6.21 to 24.36 MJ/kg.

Particle coating process, one of the main methods to improve the particle properties, is widely used in industrial production and pharmaceutical industry. For the scale up and optimization of this process, a mechanistic and detailed study is needed or numerical simulation as an alternative way. Decomposition of substances usually involves multiple chemical reactions and produces multiple substances in the actual chemical reaction. In the study, a chemical reaction flow (CRF) model has been established based on kinetic mechanism of elementary reaction, the theory of molecular thermodynamics and the sweep theory. It was established with the comprehensive consideration of the decomposition of substances, deposition process, adhesion process, desorption process, hydrogen inhibition, and clearance effect. Then the CFD-DEM model was coupled with CRF model to simulate particle coating process by FB-CVD method, and the CFD-DEM-CRF coupling model was implemented in the software Fluent-EDEM with their user definition function (UDF) and application programming interface (API). The coating process in the spouted bed was analyzed in detail and the coating behavior under different conditions were compared at the aspects of CVD rate, coating efficiency, particle concentration distribution, particle mixing index and gas concentration distribution. It is found that the average CVD rate is 6.06 × 10 −4  mg/s when the inlet gas velocity is 11 m/s and bed temperature is 1273 K, and simulation result agrees with the experimental result well. Average CVD rate and coating efficiency increase with temperature increasing, but decrease acutely with mass fraction of injected hydrogen increasing. The CFD-DEM-CRF coupling model can be developed as a basic model for investigating particle coating process in detail and depth and can provide some guidance for the operating conditions and parameters design of the spouted bed in the real coating process.

Ethylene is one of the most primary and widely used petrochemical products in today’s world and is considered as a chemical building block in the petrochemical industry. In this research, ethylene production from ethane and natural gas is evaluated in terms of cost and optimum conditions. Also, a comprehensive economic and technical comparison is made to achieve the optimal conditions for ethylene production concerning feed diversity. Nowadays most ethylene production units run with ethane feed. If it is possible to implement gas-ethylene processes with an inexpensive natural gas feed, it will be a significant step for technical and economic optimization. Thus, some methods are introduced and compared, and finally an economic review about best condition for ethylene production from ethane and natural gas/investment with regard to cost and economic efficiency of the methods is provided. The investment cost for Gas to Ethylene (GTE) and Ethane to Ethylene (ETE) processes is 363–701 million dollars per year, respectively. Also, rate of return (ROR) of 24 and 19% is calculated for GTE and ETE processes, respectively.

Nowadays, dynamic mixers are widely used in industry. But dynamic mixers have problems like low mixing efficiency and high mixing resistance. Therefore, many scholars are committed to improving the rotor inside the dynamic mixer to improve its working performance. In this paper, a new structure of spiral rotor with chamfer and perforation was designed for promoting the performance of the dynamic mixing equipment. We measured the pH value to find which rotor’s working performance is better. On this basis, a numerical simulation was conducted on the mixing angle of the two-phase fluid to explore the best working environment of the dynamic mixer. Experimental studies proved that the mixing effect of the new structure rotor was better. The simulation results showed that the mixing effect of the two-phase flow was better when it merged at 135°.

Palladium on the polymeric materials (Pd@polymer) as a catalyst is now very promising due to its great prospect for catalytic application. Such material in the form of composites is found to be stable and can be applied as catalyst in organic synthesis like Sonogashira coupling reaction. In the present work, Pd containing conjugated poly-ynes composites (Poly (1,4-bis(dodecyloxy)-2,5-diethynylbenzene) (Poly-DEB)/Pd) were synthesized by varying the addition of Pd in the range of equivalent weight of 8:4, 8:2 and 8:1, maintaining the fixed amount of 1,4-bis(dodecyloxy)-2,5-diethynylbenzene (DEB) through chemical oxidative polymerization technique. Both FTIR and UV-visible spectroscopy confirmed the interactions between DEB and Pd in the composites. The DSC data revealed the improved melting temperature as well as the crystallinity of the composites than the DEB. The PL spectra showed its florescence property. The catalytic capability of the Poly-DEB/Pd composites were examined using the Sonogashira coupling reactions, which demonstrated good yields. The suggested synthetic protocol is very facile, reproducible and beneficial for the fabrication of diverse mono and bimetallic composites with conjugated polymers. The present study also demonstrates the new example of Poly-DEB/Pd composites catalyzed Sonogashira coupling reaction. These composites have a possibility to develop as a commercial reagent in various organic synthesis subjects to its application prospects.