Catalyst Inlet Research Articles

Simulation analysis of gas-solid two-phase flow and reaction in a novel catalytic cracking reactor

A gas-solid two-phase flow reaction model was developed to evaluate the performance of a novel catalytic cracking reactor in the residue-to-chemicals (RTC) process. Coupled TFM, EMMS drag, and 12-lump kinetic models were employed to simulate the flow reaction process. The reaction temperature and product yields at the reactor exit aligned well with real industrial RTC reactor test results, indicating the reliability and effectiveness of the coupling model. Catalyst particles formed an internal circulation structure in the reactor, increasing the instantaneous catalyst-to-oil ratio. The reactor exhibited low axial and radial temperature gradients with higher reaction temperatures, accelerating the catalytic cracking rate and enhancing the selectivity for high-value products. The effects of the catalyst-to-oil ratio, catalyst inlet temperature, and feedstock mass flow rate on the flow reaction process were optimized. Results showed that both the catalyst-to-oil ratio and catalyst inlet temperature influenced the overall catalyst velocity distribution. Within the limit range, increasing the catalyst-to-oil ratio increased feedstock conversion, gasoline, LPG, dry gas, and coke yields, but decreased diesel yield. Conversely, increasing the feedstock mass flow rate showed opposite trends. Different trends in product yields were observed with varying inlet catalyst temperatures, with optimal product distribution at 973.15 K.

Study on the active regeneration characteristics of DPF in diesel-methanol dual-fuel engine under different exhaust oxygen concentrations

This study proposes a method to control exhaust oxygen (O2) concentration by adjusting the intake throttle valve, achieving intake throttling, and reducing intake airflow. The impact of exhaust O2 concentration at the inlet of the diesel oxidation catalyst (DOC) the diesel particulate filter (DPF) performance during active regeneration in diesel engines is investigated. Experiments are conducted under methanol substitution rates (MSR) of 0% and 20% to investigate how different exhaust O2 concentrations affect the performance of the DOC and DPF during active regeneration. A comparative analysis of fuel consumption and cumulative CO2 emissions during DPF active regeneration under different exhaust O2 concentrations is performed. Research results indicate that decreasing exhaust O2 concentration reduces exhaust flow, raising DOC inlet temperature. This enhancement improves catalytic conversion efficiency, accelerating the rise in DPF inlet temperature. The average conversion efficiency of DOC to unburned methanol exceeds 98.07%. After initiating DPF active regeneration, O2 concentration sharply drops, leading to elevated CO2 emissions. As soot combustion advances, the required O2 diminishes, resulting in a gradual rise and eventual stabilization of O2 emissions. Economically and environmentally, irrespective of MSR (20% or 0%), there exists an optimal exhaust O2 concentration that minimizes effective regeneration time during DPF active regeneration, achieving minimal fuel consumption and the lowest CO2 mass emissions. This study offers theoretical support for optimizing energy-saving and emission-reduction processes during DPF active regeneration.

Potential of V2O5-WO3/TiO2 catalyst usage as the secondary measure for household heating combustion unit

The active substance used in oxidation honeycomb catalysts determined for real flue gas purification usually consists of precious metals such as platinum or palladium, while the most common is the mixture of the two mentioned elements, however high prices and limited availability of these elements encourages producers for the search for new, equally or better effective alternatives. In this study V2O5-WO3/TiO2 honeycomb catalyst was tested during the combustion test with commonly sold manually loaded stove. The catalyst was installed in the flue gas duct at the stove outlet. The experimental comparison of the flue gas composition at the catalyst inlet and at the catalyst outlet was performed. Flue gas sampling took place for whole combustion periods. Relatively high conversion rates by catalyst of CO (up to 87.1%), C3H8 (up to 61.3%) and TSP (up to 17.7%) were reached, which meant that the limit values of Commission regulation for mentioned kind of equipment were met during four, not only one period (in case of non-use of the catalyst). The V2O5-WO3/TiO2 catalyst has a great potential as the secondary emission control device for achieving low mass concentration of the certain pollutants in the flue gas.

Catalytic Hydrogenation of Nitrate over Immobilized Nanocatalysts in a Multi-Phase Continuous Reaction System: System Performance, Characterization and Optimization

Nitrate catalytic reduction in a continuous system was studied in the presence of Pd-Cu macrostructured catalysts synthesized through a novel washcoating methodology of the pre-formed bimetallic powder catalyst. The present work aims to understand the behavior of the macrostructured bimetallic catalyst in the presence of different reaction conditions in order to achieve the design of an optimized facility that can produce the best catalytic results: maximum NO3− conversion with enhanced N2 selectivity. The residence time of the inlet solution and the catalyst concentration in the reactor proved to be the parameters that most influenced the conversion and selectivity due to the important role that these parameters play in the hydrodynamic conditions of the reactor. A higher loading of catalyst and lower inlet flow rates allow promoting a higher contact time between the three phases that participate in the reaction (G-L-S). The most efficient reaction conditions (three pieces of the macrostructured catalyst, liquid flow rate of 10 mL min−1, and a total gas flow rate of 200 Ncm3 min−1 (1:1 H2:CO2)) allowed obtaining an NO3− conversion of 51% with a corresponding N2 selectivity of 23%. Also, the conversion results strongly depended on the total gas flow rate used during the reaction since this assists the mixing between the three phases and promotes a greater contact that will contribute to enhanced catalytic results.

CFD Simulation of SCR Systems Using a Mass-Fraction-Based Impingement Model

Computational fluid dynamics (CFD) are an essential tool for the development of diesel engine aftertreatment systems using selective catalytic reduction (SCR) to reduce nitrous oxides (NOx). In urea-based SCR, liquid urea–water solution (UWS) is injected into the hot exhaust gas, where it transforms into gaseous ammonia. This ammonia serves as a reducing agent for NOx. CFD simulations are used to predict the ammonia distribution in the exhaust gas at the catalyst inlet. The goal is to achieve the highest possible uniformity to realize homogeneous NOx reduction across the catalyst cross section. The current work focuses on the interaction of UWS droplets with the hot walls of the exhaust system. This is a crucial part of the preparation of gaseous ammonia from the injected liquid UWS. Following experimental investigations, a new impingement model is described based on the superposition of four basic impingement behaviors, each featuring individual secondary droplet characteristics. The droplet–wall heat transfer, depending on surface temperature and impingement behavior, is also calculated using a newly parameterized model. Applying the presented approach, the cooling of a steel plate from intermittent spray impingement is simulated and compared to measurements. The second validation case is the distribution of ammonia at the catalyst inlet of an automotive SCR system. Both applications show good agreement and demonstrate the quality of the new model.

Catalyst-Accelerated Circular Cascaded DNA Circuits: Simpler Design, Faster Speed, Higher Gain.

DNA cascaded circuits have great potential in detecting low abundance molecules in complex biological environment due to their powerful signal amplification capability and nonenzymatic feature. However, the problem of the cascaded circuits is that the design is relatively complex and the kinetics is slow. Herein, a new design paradigm called catalyst-accelerated circular cascaded circuits is proposed, where the catalyst inlet is implanted and the reaction speed can be adjusted by the catalyst concentration. This new design is very simple and only requires three hairpin probes. Meanwhile, the results of a series of studies demonstrate that the reaction speed can be accelerated and the sensitivity can be also improved. Moreover, endogenous mRNA can also be used as a catalyst to drive the circuits to amplify the detection of target miRNA in live cells and in mice. These catalyst-accelerated circular cascaded circuits can substantially expand the toolbox for intracellular low abundance molecular detection.

Emission characteristics of a diesel engine with an electrically heated catalyst under cold start conditions

The high emissions of diesel engines at cold start conditions have attracted more and more attention, because the exhaust gas temperature at this condition is too low to light-off the aftertreatment system. The electrically heated catalyst (EHC) has a high potential for increasing exhaust gas temperature and thus lowering emissions from diesel engines under cold start conditions. In this study, based on a diesel engine with an aftertreatment system that an EHC was installed in the inlet of a diesel oxidation catalyst (DOC), the engine was cold started to a low-load operating point (1000 r/min, 56 N m) and the World Harmonized Transient Cycle (WHTC). The influence of the EHC on the exhaust gas temperature and emission characteristics under the two cold start conditions is investigated. When EHC-on as opposed to EHC-off, the time required for the exhaust gas temperature at post-DOC to reach 138°C was shortened by 767 s during the low-load cold start process, and the time required to reach 200°C was reduced by 418 s during the WHTC cold start process. The total conversion efficiencies of CO and HC increased by 92.8% and 50.8% respectively in the warm up process of the low-load cold start, and the increases were 39.8% and 38.5% respectively in the urban driving cycle of the WHTC cold start process. It was found that the particulate number (PN) concentration at post-DOC increased when EHC-on, and the proportion of nucleation-mode particulates also increased.

Computational Fluid Dynamics Simulation of a Fluid Catalytic Cracking Regenerator

The aim of this study is to simulate a Fluid Catalytic Cracking (FCC) Regenerator, of a local refinery, using the Fluent Ansys.13 program and subsequently to investigate the impact of the change in geometry on the unit’s performance. Three different geometrical models of FCC Regenerator were simulated. The Solid Works program was used to build up the computational domain and the commercial CFD code Ansys-Fluent 13 was used for meshing, models setup and solving. Three cases were examined: base case with a single air inlet, case one with five air inlets, and case two with five air inlets, however with the catalyst inlet axis raised by 100%. The results showed that the carbon solid mass content (used to represent the coke) decreases from 0.39 to 0.23 in the base case and to 0.12 in case one and to 0.19 in case two for the regenerated catalyst. Case one resulted in a decrease in carbon content by 100%, with a carbon monoxide emission of 10ppm (the base case at a value of 200ppm) which increased in case two to 100ppm. Furthermore the impact of air mass flow rate in case one (best case) was investigated starting with a mass flow rate of 29.5kg/s. The flow rate was further increased by 100% and 200% which resulted in a carbon mass content of 0.092 and 0.08 respectively.

Effect of Catalyst Inlet Flow Field Distribution Characteristics on Outlet NO Concentration Distribution in SCR Denitration Reactor Based on Monte Carlo Method

Selective catalytic reduction (SCR) technology plays a crucial role in flue gas denitration. The nonuniform distribution of catalyst inlet parameters causes the nonuniform distribution of NO concentration at the outlet, thus affecting accuracy of ammonia injection. Regarding this issue, this paper describes the impacts of nonuniform velocity and temperature on both the confidence of NO concentration measured at a single measuring point at the outlet and the denitration efficiency, which can provide a basis for structural optimization of SCR denitration reactor and decrease in ammonia slip. The random distribution form of velocity and temperature above the catalyst layer are derived from the actual gas volume and the actual SCR reactor model, and then the catalyst inlet boundary conditions were generated with different relative standard deviation of velocity and temperature accordingly. The confidence of outlet NO concentration measurement results can be counted by means of Monte Carlo simulation. Finally, the relation model can be obtained to calculate the confidence of outlet NO concentration measurement results at different working conditions. The results show that within the gas volume range of this work, in order to ensure the confidence of the NO concentration measurement results, the relative standard deviation of temperature before the catalyst inlet must be within 0.005 and the relative standard deviation of velocity before the catalyst inlet must be within 0.1. With the increase in relative standard difference in temperature, there is a slight decrease in the efficiency of denitration. With the different mean value of temperature, the variation range of denitration efficiency is similar to that of temperature-relative standard difference. With the different mean value of velocity, the deviation range of corresponding efficiency is similar to that of the temperature-relative standard difference. When the relative standard difference in velocity increases, the denitration efficiency decreases slightly. The greater velocity value, the decreasing range of denitration efficiency is larger than the variation range of relative standard difference in velocity.

Experimental investigation of urea injection strategy for close-coupled SCR aftertreatment system to meet ultra-low NO emission regulation

• The tailpipe NOx and PM emission satisfy CARB ultra-low emission regulation under FTP cycle. • The effect of temperature and space velocity on NO x conversion is investigated. • A high NO x conversion efficiency is observed on ccSCR with air-assisted urea nozzle. • A zonal control strategy for dual urea injection is adopted to reduce tailpipe NOx emission. • The supplemental urea injection strategy is effective to reduce tailpipe NOx emission. Worldwide automotive emission regulations for heavy-duty diesel engines are increasingly stringent, especially for nitrogen oxide (NO x ) and particulate matter (PM). The development of high-efficiency aftertreatment technologies and the optimization of the urea injection strategies are key factors for the diesel engines to meet the future regulations. In this paper, the effects of temperature and space velocity on close coupled selective catalyst reduction (ccSCR) and SCR are investigated firstly. The highest NO x conversion efficiency of ccSCR and main SCR is observed at 350 °C, and an increase of space velocity leads to a more significant decrease on NO x conversion efficiency of ccSCR than that of SCR. Then three phases of urea injection state for both nozzles are determined according to the catalyst inlet temperature in the Federal Test Procedure (FTP) cycle. Urea injection strategy is optimized by urea injection ratio calibration and urea injection strategy updating based on the characteristic of three phases, as well as NH 3 sensor feedback. Finally, the composite tailpipe NO x emission under FTP cycle is reduced below 0.027 g/kW·h, satisfying California air resources board (CARB) ultra-low NO x emission regulation with a penalty of slight increase in CO 2 emissions. However, adopting a high reactivity gasoline can improve the efficiency while maintaining the low level of NO x emissions.

Experimental and Numerical Analysis of an Innovative Mixer Geometry for Urea Injection in SCR Applications

Selective catalytic reduction (SCR), based on the injection of urea-water-solution (UWS), is one of the prevailing and more effective approaches to reduce NOx emissions in diesel engines. To improve the performance and durability of the system, it is crucial to develop reliable simulation tools able to correctly describe not only the urea conversion into ammonia and the mixing with exhaust gases but also the possible formation of solid deposits along with the engine’s exhaust line.In the present paper, two different exhaust systems for off-road applications are analyzed, both of them consisting of a diesel oxidation catalyst (DOC) followed by a diesel particulate filter (DPF), a UWS injection and a mixing device, and an SCR catalyst. Two alternative UWS mixing subsystems are evaluated, including a newly developed design. A 3D-CFD numerical analysis is carried out to assess the performance of both systems in terms of pressure drop, UWS spray, and liquid film development, in addition to flow velocities and species concentration uniformities at SCR catalyst inlet. A detailed analysis of droplet impingement on walls and liquid film development is enabled, thanks to a conjugate heat transfer (CHT) approach. Moreover, a deposit risk index is used to identify the areas of the systems where urea deposit formation is expected.Eventually, numerical results are compared with experiments on one operating condition chosen as the most challenging in terms of exhaust temperature and flow rate, both in terms of systems NOx conversion efficiency and deposit formation, showing a satisfactory agreement, thus paving the way to use the proposed synergetic numerical and experimental approach to further optimize the design and the system’s performance.

Numerical Simulations in SCR systems with Emphasis on Uniform Flow at the Catalyst Inlet

Selective Catalytic Reduction (SCR) is one of the most widely used technologies for reducing emissions from diesel engines, which are widely used in the energy world. This technology is very complex, and it is not currently possible to address all aspects of it comprehensively. This study focuses on trying to improve the distribution of the exhaust stream at the catalyst inlet using models which represent the most common geometric distributions. Four types of geometries are selected, complemented by a fifth design, which is used as a reference, to find the maximum achievable values of the parameters under study. In this case, mainly the uniformity index is addressed, which indicates how uniformly the selected variable is distributed over the particular area. The study presents possible modifications of the flue gas duct which will be generally applied.

Influence of flue gas parameters on conversion rates of honeycomb catalysts

• The most important parameter was the flue gas temperature at the catalyst inlet. • Average conversion rate of carbon monoxide was 69% in case of catalyst Cat A. • Average conversion rate of carbon monoxide was 96% in case of catalyst Cat B. • There was no dependence between C 3 H 8 conversion rate and observed parameters. • Tested manually operated stove is suitable for retrofit by catalysts installation. In this study, two honeycomb catalysts with palladium and platina-palladium as active elements were used for an oxidation of products of incomplete combustion such as carbon monoxide (CO) and propane (C 3 H 8 ) contained in flue gas produced by a small-scale stove. Catalysts were installed into the flue gas duct right behind the flue gas outlet of the wood log, and pellet stove. During the tests, the conversion rates of unburned pollutants were observed according to volume fraction of oxygen in the flue gas, space velocity of flue gas, temperature of flue gas at the catalysts inlet, and mass concentration of oxidized pollutants at the catalysts inlet. The CO conversion rates ranged between 37% and 95.4% (69% in average) in case of Cat A and 51.4% and 99.9% (96% in average) in case of Cat B. In terms of C 3 H 8 conversion rate, Cat B proved higher effectiveness (25% in average), than Cat A (4% in average). The most significant parameters were determined. The significant influence of combustion phase on C 3 H 8 conversion rate was observed in case of manually loaded stove.

CFD analysis of influencing factors on SCR denitration efficiency of sintering flue gas based on response surface methodology

Selective catalytic reduction（SCR） technology is the key technology of flue gas denitration. SCR reactors are the systems contributing to pollution-free emission if they function properly. In order to study SCR denitration chemical reaction simulation and optimize the denitration effect, the CFD analysis of SCR reactor was carried out. The realizable k-ϵ turbulence model, component transport model and chemical reaction model were used to simulate the SCR denitration reactor. Based on the response surface methodology (RSM), the effects of three factors on the denitration efficiency were studied, including catalyst inlet gas velocity, reaction temperature and NH3/NO molar ratio. The quadratic multinomial regression model of three factors affecting the denitration efficiency was established. In addition, the structure of hot air duct and guiding plate were optimized based on the non-uniform inlet temperature. The results showed that: three factors had a significant impact on the denitration efficiency, and the interaction of catalyst inlet gas velocity and reaction temperature is the most significant; the structure optimization of hot air duct and guiding plate can improve the denitration efficiency and reduce outlet NO concentration relative standard deviation, and avoid catalyst abrasion. In this paper, a suitable numerical simulation model is proposed for SCR denitration reaction, and the consideration of non-uniform inlet temperature and the proposition about taking relative standard deviation of NO concentration at the outlet as an optimization index contribute to a more practical and more reasonable structure optimization.

Fuel supply system to DOC by nanopore-ceramic tube and measurement of fuel evaporation rate

When the deposited particles in DPF is oxidized, diesel fuel is injected to the diesel oxidation catalyst (DOC) for increasing the exhaust gas temperature. It is called a secondary fuel injection. However, it is difficult to form the uniform fuel mixture. If there is high fuel concentration region, hot spots and/or coking at the catalyst inlet face, leading to the potential damage of the catalyst. Also, the fuel must be completely evaporated to avoid the emission of harmful hydrocarbons in the outer atmosphere. Non-uniform fuel supply across the catalyst inlet face may cause incomplete fuel oxidation over the DOC. Thus, we may need an alternative approach for fuel supply system in the exhaust line. In this study, we have tested a fuel supply system to DOC using nanopore-ceramic tube. The fuel is uniformly vaporized on the surface of the tube filled with the diesel fuel, which automatically flows towards the DOC. Since we could not measure the vaporized gaseous component by an electrical low pressure impactor called ELPI+, the evaporation rate was evaluated in terms of the burning velocity of the premixed flame on a Bunsen burner. It was confirmed that most of water vaporized from the ceramic tube was gaseous water vapor. As the pore size of the tube was larger, the maximum evaporation rate increased. When the tube length or the tube outer diameter was larger, the fuel evaporation was enlarged due to the larger surface area of the fuel evaporation.

Numerical Simulation of NOx Reduction in a SCR System

The stringent limits of emission standards require advanced emission control technologies to be used in modern on and off highway diesel engines. They include both in-cylinder and aftertreatment measures where the latter now have become almost mandatory. Selective catalytic reduction aftertreatment systems are widely used for nitrogen oxide (NOX) conversion in exhaust gases into harmless N2. To reduce time and costs, at the design stage of SCR systems numerical modelling is applied. Mathematical models and methods providing high prediction accuracy with and acceptable level of computational efforts are required. In this work an approach for complete simulation of SCR systems based on the coupling of commercial CFD software with developed multichannel 1D catalyst model is presented. The first one is used to carefully describe processes occurring upstream in the catalytic converter, particularly, during urea water solution injection and flow mixing. As a result, the distributions of flow parameters at catalyst inlet are derived. They are subsequently imported as boundary conditions into a developed multichannel catalyst model that allows one to take them into account when calculating NOx conversion efficiency. Based on the proposed approach a SCR system was simulated. The effect of non-uniform distributions of NH3 concentration and the gas flow velocity at the catalyst inlet on its performance was investigated. It has been shown that they have a great impact on NOX conversion and should be taken into account during the catalyst modelling.

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Hydrotreated vegetable oil (HVO), a glycerol-derived biofuel (blended with diesel fuel at 20% v/v, Mo·bio®) and biodiesel produced through the esterification of residual free fatty acids from the palm oil industry (pure and blended with diesel fuel at 20% v/v), all of them considered as advanced biofuels as defined in the Directive EU/2018/2001, were tested in a Euro 6 diesel vehicle equipped with ammonia-SCR. Tests were carried out in a chassis dyno at warm (24°C) and cold (−7°C) ambient conditions following the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). The efficiency of the SCR when changing the fuel was also analysed. Regarding vehicle performance, fuel properties were mainly relevant at warm conditions. Because of the lower EGR rate, NOx emissions upstream of the SCR were higher at cold temperature, mainly during the low and the extra-high speed phases of the WLTC. CO and THC emissions were only important at the beginning of the cycle and at −7°C. HVO presented advantages regarding these compounds, while the worse cloud point of biodiesel led to higher emissions. As expected, engine-out NOx emissions were very sensitive to the EGR rate, HVO showing a slightly better behaviour because of its high cetane number. The SCR efficiency was mainly affected by the exhaust gas temperature, although fuel-derived effects were also significant. In fact, a more appropriate NO2/NOx ratio at the catalyst inlet for HVO and a higher hydrocarbon concentration at the low-speed phase for B20 contributed to a lower tail-pipe NOx emissions at −7°C. The oxygen content of biodiesel-based fuels (B100 and B20) led to lower particle number with respect to diesel fuel. Despite its nil aromatic content, the higher EGR rate and the extremely superior autoignition trend of HVO led to higher particle number under high engine load and warm conditions.

Numerical Simulation of the Gas-Solid Two-Phase Flow-Reaction Process in a Maximizing Isoparaffin Process Reactor.

The process of the fluid catalytic cracking (FCC) is accompanied by complex physical and chemical reactions and phase transition processes. For the FCC process–maximizing isoparaffin process (MIP), coupled simulation and optimization of flow reaction can meet the requirements for the design and operation of high efficiency, low energy consumption, low pollution, and low cost in the catalytic device. A combination of Eulerian–Eulerian model and 11-lump kinetic model is adopted to simulate the flow-reaction process of gas–solid two-phase of an industrial MIP riser reactor. A drag model based on the energy-minimization multiscale model established by Yang is incorporated into FLUENT through a user-defined function (UDF). The temperature distribution of the catalyst and the concentration of each product component at the outlet are in good agreement with the industrial measured data, which indicates that the established coupling model of flow reaction and drag model are reliable and effective. The two operating variables of the catalyst-to-oil ratio and catalyst inlet temperature are explored their effects on the flow-reaction process of FCC gas–solid two-phase. In the prelifting zone, the velocity of catalyst particles presents parabolic distribution. In the first reaction zone, the maximum velocity of catalyst particles is about 1/2 of the radius of the riser. In the second reaction zone, the maximum particle velocity of catalyst is located in the central region, with a slight increase in about 1/2 of the radius of the riser. The increase in catalyst-to-oil ratio leads to the decrease in the yield of diesel oil and the increase in yields of gasoline, liquefied petroleum gas, propylene, and dry gas. The changes in the catalyst inlet temperature affect the product distribution of the outlet component, which can provide an important guiding significance.

Investigation of Urea Uniformity with Different Types of Urea Injectors in an SCR System

Heavy-duty diesel engines in highway use account for more than 40% of total particulate and nitrogen oxide (NOx) emissions around the world. Selective catalytic reduction (SCR) is a method with effective results to reduce this problem. This research deals with problems in the urea evaporation process and ammonia gas distribution in an SCR system. The studied system used two types of urea injectors to elucidate the quality of ammonia uniformity in the SCR system, and a 12,000-cc heavy-duty diesel engine was used for experimentation to reduce NOx in the system. The uniformity of the generated quantities of ammonia was sampled at the catalyst inlet using a gas sensor. The ammonia samples from the two types of urea injectors were compared in experimental and simulation results, where the simulation conditions were based on experimental parameters and were performed using the commercial CFD (computational fluid dynamics) code of STAR-CCM+. This study produces temperatures of 371 to 374 °C to assist the vaporization phenomena of two injectors, the gas pattern informs the distributions of ammonia in the system, and the high ammonia quantity from the I-type urea injector and high quality of ammonia uniformity from the L-type urea injector can produce different results for NOx reduction efficiency quality after the catalyst process. The investigations showed the performance of two types of injectors and catalysts in the SCR system in a heavy-duty diesel engine.

Efficient Processing of Reactions Involving Diazonium Salts: Meerwein Arylation in an Impinging-Jet Reactor

This work reports a novel approach for performing high-throughput synthesis of Meerwein arylation in an impinging-jet reactor. The multistep reaction was performed in a single reactor via in situ diazonium salt generation followed by Meerwein arylation. The work involves many iterations between experiments and simulations (where we integrate simulating the flow, heat transfer, and reaction simultaneously) for optimization of conditions in an inverted impinging-jet reactor. The effect of design variables viz. catalyst concentration, inlet temperature, and monomer mole ratio on the yield of the desired product was studied in detail, and the simulation results were used to plan the continuous experiments. An infrared camera was used to monitor the transient reactor temperature for steady-state analysis. The lab-scale inverted impinging-jet reactor with over 93% isolated yield can offer a space-time yield of 277.78 tons/m3/day. The numbering-up of an inverted impinging-jet reactor can be an effective way for cleaner production of products through typical Meerwein arylation.