The force exerted on particles is of great significance to the flow and reaction characteristics of particles in gasifier. In this study, the unbalanced thrust, especially its magnitude, of a single char particle induced by chemical reactions during combustion process is investigated numerically, based on the random distribution of active sites. It is revealed that the nonuniform distribution of active sites directly leads to the nonuniform release of gaseous products, which accounts for the net induced thrust of particles. The effects of active site ratio, ambient gas temperature and particle diameter on the induced thrust of reaction particle were investigated. The results show that the induced thrust on particles could be equal to the magnitude of particle gravity. The induced thrust decreases with the increase of active area and particle diameter. And it is enhanced with the increase of ambient temperature.

Because of very high potential barrier for thermionic emission and trap-assisted charge recombination, photocatalytic reaction rate that determined by semiconductor-cocatalyst interfacial electron transfer severely deviates from linearity to the photocatalyst dosage or to the light intensity. This makes it challenging to maximize utilization of practical irradiation by referring the parameters evaluated from method used in conventional catalysis. We here develop a model and predict that photocatalytic reaction rate positively correlates to photocatalyst concentration under weak illumination while the correlation becomes negative under intense irradiation. The theoretical simulation that matches the experimental values can be used to guide maximizing photocatalytic photon utilization under various intensity of irradiation. The strong correlation can rationalize photocatalytic evaluation instead of obtaining a numerically high value by excessively lowering the denominators. To realize efficient utilization of real-time changing sunlight, we propose a reactor configuration that can optimize the amount of photocatalyst participating into the reaction.

In this study, a new electrolyte system consisting of tetrabutylphosphonium 4-(methoxycarbonyl) phenol ([P4444][4-MF-PhO]) ionic liquid and acetonitrile (AcN) was developed as CO2 electroreduction electrolyte to produce oxalate, and the mechanism was studied. The results showed that using the new ionic liquid-based electrolyte, the reduction system exhibits 93.8% Faradaic efficiency and 12.6 mA cm-2 partial current density of oxalate at -2.6 V (vs. Ag/Ag+). The formation rate of oxalate is 234.4 μmol cm-2 h-1, which is better than that reported in the literature. The mechanism study using density functional theory (DFT) calculation revealed for the first time that [P4444][4-MF-PhO] IL can effectively activate CO2 molecules through ester and phenoxy double active sites, stabilize the reaction intermediate. The potential barriers of the key intermediates *CO2- and *C2O42- formation by induced electric-field was reduced in the phosphonium-based ionic environment, which greatly facilitates the activation and conversion of CO2 molecules to oxalate.

A gas-liquid stirred tank reactor (STR) has some problems, such as low mass transfer efficiency, high exhaust gas oxygen concentration, and low product conversion rate, due to limitations of stirring speed and input power. This article proposes a method to enhance the gas-liquid mass transfer in a STR using circulating jet internals. When a circulating jet is added, the average bubble size in the reactor is reduced to 1.26 mm, and the overall gas holdup is increased to 8.23%, which is an increase of 3.62 times of the original STR. The gas-liquid volumetric mass transfer coefficient is increased to 0.05556 s-1, which is 4.84 times of the original STR. The unit volume power is increased by only 1.4 times. These data provide references for the design and scale-up of new jet STRs.

To alleviate the greenhouse gas emissions by the chemical industry, electrification has been proposed as a solution where electricity from renewable sources is used to power processes. The adoption of renewable energy is complicated by its spatial and temporal variations. To address this challenge, we investigate the potential of distributed manufacturing for electrified chemical processes installed in a microgrid. We propose a multi-scale mixed-integer linear programming model for locating modular electrified plants, renewable-based generating units, and power lines in a microgrid that includes monthly transportation and hourly scheduling decisions. We propose a K-means clustering-based aggregation disaggregation matheuristic to solve the model efficiently. The model and algorithm are tested using a case study with 20 candidate locations in Western Texas. Additionally, we define a new concept, “the Value of the Multi-scale Model”, to demonstrate the additional economic benefits of our model compared with a single-scale model.

As key components of antifouling material surfaces, the design and screening of polymer molecules grafted on the substrate are critical. However, current experimental and computational models still retain an empirical flavor due to the complex structure of polymers. Here, we report a simple and general strategy that enables multi-scale design and screening of easily synthesized functional polymer molecules to address this challenge. Specifically, the required functions of the antifouling material are decomposed and assigned to different modules of the polymer molecules. By designing different modules, a novel bio-inspired polymer with three zwitterionic poly (sulfobetaine methacrylate) (PSBMA) chains, three catechol (DOPA) anchors (tri-DOPA-PSBMA), and a tris(2-aminoethyl) amine (TREN) scaffold were screened out. Moreover, it was successfully synthesized via an atom transfer radical polymerization (ATRP). The excellent performance of tri-DOPA-PSBMA with a versatile and convenient grafting strategy makes it a promising material for marine devices, biomedical devices, and industrial applications.

An economical and highly uranium extraction from seawater remains a crucial task for energy sources and environmental safety. Aiming for improving the mass transfer rate of uranium from seawater, a new synthetic strategy was adopted to synthesize 2D-open channel microporous bio-adsorbent for uranium extraction from seawater. Herein, a vapor phase modification approach was adopted to graft divinylbenzene(DVB), and polyacrylonitrile(AN) onto the surfaces of microporous frameworks via a free radical polymerization method. The post-synthetic functionalization was carried out by hydrothermal process, where amidoxime groups are structure-directing agents to trap uranium. Further, amidoxime groups not only enhanced hydrophilicity but also adjusts adsorbents pKa. AO-Fc faces minimum interference of competing ions and achieves a high uranium adsorption capacity of 8.57±0.02 and 409±1 mg/g in seawater and simulated solution. Despite its stable structure, AO-Fc exhibits a long life span and negligible weight loss revealed AO-Fc could be applied as a potential adsorbent for radionuclides

In order to address the challenge of pressure swing adsorption system optimization, an optimization framework based on pseudo transient continuation method was used and vacuum rapid pressure swing adsorption process for oxygen production as a typical example. A pseudo transient model library was established and a robust two-stage dynamic tearing model was proposed to deal with the cyclic steady state conditions. Furthermore, the time constants were discussed and a practical time constant strategy and expressions were proposed for the stability and efficiency of calculation. Finally, reduced successive quadratic programming and time relaxation algorithm were used for the optimization of the two systems respectively, and the optimization results showed that although the simulation time of pseudo transient system is slightly higher than that of single discretization system, the optimization expense of single discretization system in two cases were 5.7 times and 11.6 times of that of pseudo transient system respectively.

In this work, stationary states in nonequilibrium plasmas of chemical reactions that can produce hydrogen are explored, namely the water splitting and water gas shift reactions. For both reactions, the effluent from the reactor at long gas residence times in the plasma was found to be independent of the influent speciation. In other words, feeding the reactor either 0.1 H2O or 0.1H2+0.05O2 by mole produced the same effluent composition, and similarly, feeding the reactor 0.1CO+0.1H2O produced nominally the same effluent as 0.1CO2+0.1H2. For both reactions, the effluent from the plasma was found to be very far from local equilibrium at the total pressure and background temperature of the reactor. An important conclusion of this work is that special attention must be paid to the recombination zone in plasma chemical processes. The recombination zone tends to drive the gas composition from plasma stationary states back towards local equilibrium.

This paper presents a novel energy flow redistribution methodology to achieve optimal operation of heat exchanger networks (HENs). The proposed method aims to manipulate the propagation path of a disturbance through the network to reduce its impact on utility consumption. Specifically, an optimization problem is formulated to generate new duty targets for heat exchangers of the network when a disturbance is encountered. Subsequently, a feedback control system is designed to track these targets by manipulating bypasses around the process heat exchangers. The effectiveness of the proposed framework is illustrated with the help of three benchmark examples. The proposed approach can handle disturbances in inlet as well as target temperature, inlet flow and heat transfer coefficient of individual heat exchangers.

The dissociation conditions of hydrate in clayey silts are of great significance for its efficient production. In this work, the dissociation conditions of methane hydrate in clayey silt cores were experimentally measured by step-heating method. Various cores including quartz powder, montmorillonite and South China Sea sediments were used for investigation. The results showed that the dissociation temperatures of methane hydrate in clayey silt cores depressed compared to bulk hydrate. In comparison to grain size, salinity and lithology had a more significant influence on the equilibrium temperature depression. A water activity meter was used to measure the water activity in clayey silt cores. The influence of salt and minerals on water activity was investigated. By combining the measured water activity data with the Chen-Guo model, a novel water activity measurement method (WAM) for the hydrate dissociation conditions prediction was proposed. The predicted results are in good agreement with the experimental data.

Yttrium-doped barium cerate (BaCe0.8Y0.2O3-δ, BCY) is the most widely studied proton conducting material and is frequently fabricated as dense membranes for hydrogen separation. However, the difficulty to prepare dense BCY membranes is the extremely high sintering temperature, normally higher than 1500 oC. Herein, the BCY 7-channel hollow fiber membrane was prepared by one-step thermal processing (OSTP). It proved that adding Co2O3 as sintering aid is beneficial to the densification and 1wt% Co2O3 was the optimum addition to form a homogeneous phase structure. The dense sintering temperature was greatly reduced from over 1500 to 1350 oC. The hydrogen permeation flux of the BCY hollow fiber membrane reached up to 0.34 ml min-1cm-2 at 900 oC. The long-term stability test last for 300 h. The properties of OSTP samples were demonstrated to be essentially higher than samples made by conventional ceramic hollow fiber fabrication methods.

The gas-liquid two-phase flow pattern, absorption rate and pressure drop of CO2 absorbed into the aqueous solution of the task-specific ionic liquid (1-aminopropyl-3-methylimidazole tetrafluoroborate [Apmim][BF4] and 1- hydroxyethyl-3-methylimidazole tetrafluoroborate [OHemim][BF4]) and halide-free ionic liquid 1- butyl -3-methylimidazolium methylsulfate [Bmim][CH3SO4] were investigated in a microreactor. The absorption mechanism of the three ionic liquids was analyzed employing the 13C NMR spectroscopy. The [Apmim][BF4] was found to have the best ability of CO2 capture compared to the other two ionic liquids, as chemical absorption occurred between [Apmim][BF4] and CO2, while only physical absorption took place between [OHemim][BF4] / [Bmim][CH3SO4] and CO2. The sequence of CO2 absorption rate in three ionic liquid aqueous solutions is: [Apmim][BF4] > [Bmim][CH3SO4] >[OHemim][BF4]. Furthermore, the effects of gas-liquid flow rate and ionic liquids concentration on CO2 absorption rate and pressure drop were studied, the pressure drop models based on various flow patterns were proposed.

Editorial – The third “Futures” issueThis month’s volume of AIChE Journal is the third “Futures” issue. I think now we’ve established a tradition. This is my favorite issue each year.Each year we invite a group of early career researchers to contribute their pioneering works. I have sought the input of the AIChE Journal editorial team and consulting editorial board to identify contributors. The criterion is that the prospective author be seven or less years removed from her or his initial appointment as an academic, industrial, or national lab researcher.During the publication year we have a session at the Annual AIChE meeting where several of the authors have the opportunity to present their research. (This being the year of COVID-19, these presentations will unfortunately be virtual.)The “Futures” issue parallels the annual “Founders” issue; while the “Founders” issue celebrates the scholarly legacies of the greats from our profession, the “Futures” issue recognizes the research of emerging scholars.I hope that you enjoy this third installment of the “Futures” series.On behalf of the AIChE Journal editorial team, we look forward to your input and suggestions. As always, thanks for your support of

The effects of particle concentration and size on hydrodynamics and mass transport in a slurry bubble column were experimentally studied. With increasing particle concentration, the averaged gas holdup, gas holdup of small bubbles and gas-liquid volumetric mass transfer coefficient decreased, while the gas holdup of large bubbles increased slightly. With increasing particle size, the averaged gas holdup and kla remained unchanged when the particle size increased from 55 to 92 m, but decreased significantly when the particle size was further increased to 206 m. A liquid turbulence attenuation model which could quantitatively describe the effects of particle concentration and size was first proposed. Semi-empirical correlations were obtained based on extensive experimental data in a wide range of operating conditions and corrected liquid properties. The gas holdup and mass transfer coefficient calculated by the correlations agreed with the experimental data from both two-phase and three-phase bubble columns

Error-in-variables model (EVM) methods require information about input and output measurement variances when estimating model parameters. In EVM, using replicate experiments for estimating output measurement variances is complicated, because true values of inputs may be different when multiple attempts are made to repeat an experiment. To address this issue, we categorize attempted replicate experiments as: i) true replicates (TRs) when uncertain inputs are the same in replicated runs and ii) pseudo-replicates (PRs) when measured inputs are the same, but unknown true values of inputs are different. We propose methodologies to obtain output measurement variance estimates and associated parameter estimates for both situations. We also propose bootstrap methods for obtaining joint-confidence information for the resulting parameter estimates. A copolymerization case study is used to illustrate the proposed techniques. We show that different assumptions noticeably affect the uncertainties in the resulting reactivity-ratio estimates.

A bubble coalescence model for a solution with a nonionic surfactant and with a small bubble approach velocity was developed, in which the mechanism of how coalescence is hindered by Marangoni stress was quantitatively analyzed. The bubble coalescence time calculated for ethanol-water and MIBC-water systems were in good agreement with experimental data. At low surfactant concentrations, the Marangoni stress and bubble coalescence time increased with bulk concentration increase. Conversely, in the high concentration range, the Marangoni stress and coalescence time decreased with bulk concentration. Numerical results showed that the nonlinear relationship between coalescence time and surfactant concentration is determined by the mass transport flux between the film and its interface, which tends to diminish the spatial concentration variation of the interface, i.e., it acts as a “damper”. This damping effect increases with increased surfactant concentration, therefore decreasing the coalescence time at high concentrations.

Economical uranium adsorption from seawater remains a crucial task for energy and environmental safety. Aiming for improving the mass transfer rate of uranium adsorption. Herein, a novel 2D porous aromatic framework(PAF) based on nucleophilic substitution of 2,5-dichloro benzonitrile was synthesized, with an ordered prous structure, excellent stability and selectivity of uranium extraction from seawater. PAF shows excellent uranium adsorption capacity of 637 mg/g and 3.22 mg/g in simulated and real seawater because of highly accessible pores on the walls of open channels. In addition, benefiting from the super-hydrophilicity due to the presence of amidoxime groups attributes high selectivity and ultrafast kinetics with an uptake rate of 0.43±0.03 mg/g.day and allowing half-saturation within 1.35±0.09 day. This strategy demonstrates a potential of PAF not only in uranium trap but also possess a power to monitor water quality. This technique can be extended in other applications by sensible planning target ligands