Chemical Engineering and Processing - Process Intensification最新文献

Separation of catalyst dust from gas in a fluidized bed reactor is an important process. A new solid-gas separator with arc settlers was developed, in which a stable wave flow pattern of the dusty gas flow is formed. The model was based on the RANS approach using the Reynolds Stress Model for the turbulence closure and the Discrete Phase Model. Validating the simulation results with the test data showed good convergence, no more than 6% in the pressure drop and less than 15.5% in collection efficiency at different inlet gas velocities. The CFD study revealed that with a dusty gas inlet velocity of no more than 1 m/s and a catalyst particle larger than 20 μm, efficiency close to 100% is achieved with a pressure drop of less than 60 Pa. Maximum efficiency is achieved when the number of rows of the arc settlers with 40 mm diameter is 8.

Furfural production generates wastewater characterized by high concentration, strong acidity, and poor biodegradability, necessitating treatment before discharge. The Fenton process, known for its cost-effectiveness, is widely used for industrial wastewater treatment. However, it has limitations such as a narrow pH operating range and significant secondary pollution. To optimize this, researchers have explored combining Fenton with other processes, yet few have studied its synergy with O₃. This study investigates the advantages of O₃/Fenton coupling in treating furfural wastewater, comparing the capabilities of O₃, O₃/H₂O₂, Fenton, and O₃/Fenton processes. Results show that ozone-Fenton coupling exhibits superior industrial treatment performance. Post-treatment, the wastewater's B/C ratio reached 0.43, TOC removal rate was 33.6%, and ozone utilization efficiency was 74.6%, surpassing other methods. UV absorption spectra analysis indicated enhanced degradation of aromatic compounds, transforming them into smaller organic molecules. This study highlights ozone-Fenton coupling as a low-cost, effective enhancement for furfural wastewater treatment, offering significant guidance for future research in this field.

Ammonia is crucial as it serves as a key nitrogen source in fertilizer production to enhance crop growth and as an emerging energy carrier due to its high hydrogen content and ease of liquefaction. Despite various technological changes proposed and implemented since its inception, the Haber-Bosch process remains the predominant method for ammonia production. We first give a bird's eye view of current ammonia synthesis technologies available based on the latest trends, to justify why we think the conventional Haber-Bosch process is still a relevant technology worth investigation for further improvement. We review the engineering design modifications within the ammonia synthesis loop, examining improvements in the efficiency of ammonia synthesis. This review gives an overview of recent research and advancements focused on process intensification within the loop and its individual key components, i.e., the reactor and the catalyst, separation, and purge gas recovery technologies. It highlights significant progress and explores potential future directions in these areas.

In this study, two natural deep eutectic solvents (NADESs) were prepared from natural hydrogen bond donors (HBDs) based on sugar, namely fructose and sucrose, alongside H₂O, and choline chloride as a hydrogen bond acceptor (HBA). The prepared NADESs were used as functionalizing agents with multiwall carbon nanotubes (MWCNTs), and the functionalized MWCNTs were used as adsorbents of Pb(II) lead ions from aqueous solution. The analyses demonstrated that MWCNTs functionalized with sucrose-based NADES to have more sub-stems and functional groups than the MWCNTs functionalized with fructose-based NADES, providing more possible sites for Pb(II) adsorption. The time dependence of Pb(II) adsorption onto these novel adsorbents was found to be better described by a pseudo-second-order kinetic model. Additionally, the Langmuir model better fits the adsorption data due to its higher coefficient of determination. Finally, the operating conditions (pH, adsorbent concentration, and contact time) were optimized using the Box-Behnken model, which demonstrated pH to exert greater influence on the adsorption process than the other studied factors. To the best of our knowledge, this study is the first to apply NADESs as emerging functionalizing agents for carbon nanomaterials in the removal of heavy metals from synthetic wastewater.

Compared with traditional heating, microwave heating has unique advantage and can enhance the chemical reaction. It is a promising technology for catalytic degradation of VOCs gas. Here we prepared a structured catalyst (Mn–Co/SiC) suitable for VOCs degradation under microwave. The catalyst shown excellent stability under microwave heating and microwave empowered the catalyst with good water resistance. Microwave heating exhibits high energy efficiency. Density functional theory is employed to investigate the microwave-enhanced catalytic degradation of VOCs. The theoretical calculation results indicate that the adsorption energy is more negative under microwave electric field, suggesting that microwave electric field is conducive to the activation of benzene. The electrons on the adsorption surface of the catalyst are redistributed to different degrees under the action of different microwave electric fields, thus affecting the activation of adsorbed molecules and chemical reaction process. The local density of states further reveals that electric fields may facilitate the electron transport.

This study investigates the effects of various inner cylinder configurations on micromixing and fluid dynamics within a Taylor-Couette (TC) reactor using the inner cylinders with different surface designs, including the traditional smooth-surfaced rotor cylinder. The four innovative inner cylinders were specifically designed with axial corrugations (N40 and N80) and three-dimensional rough surfaces (NZ40 and NZ80). Micromixing efficiency was assessed experimentally using the iodide-iodate reaction as a probe. To further understand the impact of the rotors' surface structures on micromixing, computational fluid dynamics (CFD) modelling was utilized to analyse the fluid dynamics within the TC reactor. An incorporation model was employed to calculate the micromixing time. The experimental findings reveal that the segregation index decreases with increasing rotation speed for all inner cylinders. Besides, NZ80′s micro-mixing efficiency surpasses that of its counterparts, NZ40, N40, and N80. The CFD modelling results underscore the significant influence of the inner cylinder's surface configuration on the turbulence dissipation rate and volume probability distribution, which are likely to contribute positively to the micromixing efficiency within the TC reactor. Furthermore, the empirical correlations obtained have been established to understand the micro-mixing time within TC reactors using different rotating cylinders.

As a typical hazardous solid waste, improper treatment of waste cathode carbon (WCC) will cause great harm to animals and plants and their living environment. In order to make the treatment of WCC more simple, efficient and clean, this paper mainly adopts the method of microwave roasting and introducing water vapor to make the fluoride in WCC melt at high temperature and be absorbed by water vapor. The effects of water flow rate, reaction temperature, reaction time, material particle size and other important factors on the defluorination efficiency of WCC were studied by single factor experiment. In this paper, the response surface method (RSM) was used to obtain and verify the best results of the experiment, and the optimum process conditions of water vapor enhanced microwave roasting WCC defluorination were determined: the reaction temperature was 1100 °C, the reaction time was 2.8 h, and the water flow rate was 3.2 mL·min⁻¹. Under this condition, the defluorination effect of WCC is the best. The predicted value of defluorination efficiency of WCC is 99.85 %, and the actual value is 99.8 %.

Chemical valorization of methane (CH₄) via modular electrified reactors could represent a profitable avenue for biogas producers. Ethylene (C₂H₄) is the most valuable product due to its large demand that results in high energy cost and carbon emissions. However, alternative electrified processes proposed so far cannot compete with the state-of-the-art fossil route in terms of energy efficiency. The catalytic plasma reactor presented in this work achieves 34.4 % C₂H₄ yield from non-oxidative CH₄ coupling, by integrating a bimetallic Pd-Ag catalyst on the surface of a 3D-printed structured electrode in a nanosecond-pulsed-discharge plasma reactor. This performance sets a new benchmark for alternative C₂H₄ production, potentially relying purely on renewable energy. Onsite energy generation via the excess hydrogen produced in the process could allow recovery of 16 % of the input energy. Moreover, the process produces solid carbon deposit that can be collected on the surfaces in proximity of the plasma discharge. This residue shows amorphous features and significant incorporation of metal particles coming from the electrodes surface. Hence, its low surface area hampers its application as carbon black analogue.

The detection of micropollutants in surface and groundwater bodies has drawn global concern due to their environmental persistence and risk to human and aquatic life. The dielectric barrier discharge (DBD) plasma reactor was employed to degrade the micropollutant 2,4-dichlorophenol (2,4-DCP). The efficiency of the reactor was investigated, and the plasma degradation process was intensified by introducing three eco-friendly oxidants, sodium percarbonate (SPC), sodium persulfate (SPS), and hydrogen peroxide (HPO), into the reactor. Results indicated that 2,4-DCP removal increased from 62.73 % to 76.37 %, 81.93 %, 100 %, and 90.02 % when 1 mM SPC, 1 mM SPS, 3 mM HPO, and 1 mM SPS + 0.33 mM SPC was added to the wastewater solution, respectively. The synergy between the oxidants and the plasma in the DBD reactor was also explored. The largest synergistic factor (1.792) was achieved when 3 mM HPO was added to the DBD reactor, followed by 0.089 for 1 mM SPC, 0.07 for 1 mM SPS, and 0.041 for 1 mM SPS+0.33 mM SPC. The main active species that catalyzed 2,4-DCP degradation were hydroxyl and sulfate radicals, and introducing the oxidants augmented their production in the solution. The synergy between the DBD+SPS+SPC led to a 58.7 % total organic carbon removal. In conclusion, the 2,4-DCP degradation intermediates and mechanisms were deduced accordingly. The findings reaffirm the effectiveness of the oxidant-coupled DBD reactor in the degradation of micropollutants.

An External Heat-Integrated Air Separation Column (E-HIASC) process is a promising air separation technology. This study focuses on the operational stability of the optimized E-HIASC process for separating nitrogen, oxygen, and argon mixtures. The operation stability of process is achieved through an Adaptive Generic Model Control (AGMC) scheme which is designed by incorporating the identified E-HIASC state-space dynamic model into the controller algorithm. The controller synthesizes the Generic Model Control (GMC) algorithm, decoupled ARX model, and Unscented Kalman Filter (UKF) algorithm to enable the auto-regression and exogenous (ARX) for model identification and the UKF algorithm to estimate time-varying parameters and compute unmeasured E-HIASC state parameters required in the GMC algorithm. A Generic Model Control (GMC) and Multivariable PID (M-PID) control schemes were also designed for benchmarking study. Simulation results show that an AGMC scheme performs better than the GMC and M-PID schemes in tracking the product concentration set point and disturbances rejection.