Mixing Unit Research Articles

Enhancing Vinyl Chloride Product Yield By Optimizing Operating Conditions In Plug Flow Reactor With Al2O3 Catalyst

Vinyl chloride (VC) is a colorless stable gas produced through a complex process with many interactions in reaction and separation. This study aims to improve mass and energy efficiency in vinyl chloride production through process simulation with HYSYS V.11. The process was modified using a plugged flow reactor (PFR) with an Al2O3 catalyst and a simplified distillation column. The method involves recycling the liquid product from the distillation column back to the mixing unit as a feed. The results show that energy efficiency improves with the reduction of the reactor's heat flow requirement from 1.009×107 kJ/h, and to 4.689×106 kJ/h, and distillation of the 2.82×106 kJ/h to 1.368×106 kJ/h. Mass efficiency also increased, with vinyl chloride yields rising by 118%, from 2572 kg/h to 3045 kg/h. In conclusion, these process modifications have succeeded in reducing energy consumption and increasing production significantly, making the process more efficient and energy friendly. Further research is suggested to optimize the use of waste heat. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Measurement and optimization of sustainable urban form elements in New Urban districts using multi-source data

IntroductionAt the crucial stage of China’s transition from extensive expansion driven by external factors to intensive, connotation-focused development, scientifically optimizing the spatial form of new urban districts, promoting dynamic and adaptive spaces, and enhancing the quality and diversity of urban environments are issues of substantial importance.MethodsBased on urban morphology, this study proposes that high street accessibility, appropriate building density and typology, and a sufficient degree of functional mixing are the foundations of spatial morphology for promoting sustainable urban development. Using spatial syntax, a spatial matrix, and mixed-function indices, this study measures urban spatial morphology elements and explores differences and rhythms in sustainable spatial morphology in new urban districts with varying development functions and cycles.ResultsThe results of the study show that: 1) the overall synergy of the accessibility spatial network in the new urban districts of Yinzhou and Xianlin is high. The building typology was dominated by mid-rise slab and enclosed types, low-rise enclosed types, and high-rise slab types, while the multistory high-coverage forms were interspersed with intervals. 2) Development in new urban districts primarily adopted a large land plot development mode with a single function. The degree of multifunctional mixing was observed to be relatively low. The dual-functional mixing degree in the Yinzhou New Urban District is higher than that in the New Xianlin urban district. 3) A significant level of overlap was observed among functional mixing, accessibility, building density, and typology. Of the functional mixing units, 42.41% of the dual-function and 78.57% of multi-function types were clustered in high-value areas of urban vitality. Additionally, 50.25% of dual-function and 85.71% of multi-function units were aggregated in high-accessibility areas.DiscussionThe mixed-use of sites contributes to the creation of urban vitality and sustainability, and the effect of the correlation between mixed-functionality and accessibility is more pronounced when mixed units involve utility land. The research results provide a reference for evaluating the current sustainable challenges of spatial patterns and offer specific tools for optimizing new urban districts.

CFD-based optimization of a high-throughput recycle micromixer

The present paper uses computational fluid dynamics (CFD) and the response surface method (RSM) to optimize the performance of a novel high-throughput recycle micromixer. The micromixing of DI water and blood plasma with various thermophysical properties is simulated for a broad range of DI water Reynolds numbers (50 <ReDI< 400). The impacts of geometrical parameters and ReDI are assessed on the mixing index (MI) and pressure drop (Δp). It is found that the chaotic advection can be enhanced by changing effective parameters due to the recirculating flow in feedback channels and vortex generation in mixing chambers. Accordingly, the channel depth has a major effect on MI and Δp in such a way that when the channel depth changes from 50 to 1000 μm, MI is augmented from 23 % to 73.25 % and Δp is reduced from 75.171 kPa to 12.85 kPa when ReDI= 400. It is revealed that MI is an enhancing function of ReDIand the number of mixing units. Besides, the figure-of-merit (FoM) analysis shows that the proposed micromixer gives a much greater FoM compared to the micromixers with ordered flow patterns when Re is an order of 50. The RSM provides two mathematical correlations for MI and Δp to obtain an optimal recycle micromixer that can be efficiently utilized in biological and clinical applications.

Numerical simulation and optimization of gas premixing structures for tail gas incinerators

It is a common practice for chemical refinery tail gases to be treated in an incinerator and then released into the atmosphere. However, tail gas combustion is a key component in ensuring that the treatment process meets the relevant standards. In this paper, a vertical tail gas incinerator gas premixing structure design is proposed, aiming to improve the gas mixing effect. Based on the basic structure of the right-hand gas distribution pipe and the single-layer fan mixer at the throat, three new structures are proposed. The five new gas-premixing structures were combined into eight new structures. A series of numerical simulations were performed for one prototype premixed structure and five new premixed structures, respectively. The gas premixing structures were screened, evaluated, and optimized using gas mixing inhomogeneity and pressure loss as control parameters. Finally, the premixing structure with the best combination for the mixing unit was selected. This study is of great significance for improving the effectiveness of tail gas incineration in chemical refineries and protecting the ecological environment.

Application of Microfluidic Devices for Automated Two-Step Radiolabeling of Antibodies.

Radioimmunoconjugates (RICs) composed of tumor-targeting monoclonal antibodies and radionuclides have been developed for diagnostic and therapeutic application. A new radiolabeling method using microfluidic devices is expected to facilitate simpler and more rapid synthesis of RICs. In the microfluidic method, microfluidic chips can promote the reaction between reactants by mixing them efficiently, and pumping systems enable automated synthesis. In this study, we synthesized RICs by the pre-labeling method, in which the radiometal is coordinated to the chelator and then the radiolabeled chelator is incorporated into the antibodies, using microfluidic devices for the first time. As a result of examining the reaction parameters including the material of mixing units, reaction temperature, and flow rate, RICs with radiochemical purity (RCP) exceeding 90% were obtained. These high-purity RICs were successfully synthesized without any purification simply by pumping three solutions of a chelating agent, radiometal, and antibody into microfluidic devices. Under the same conditions, the RCP of RICs labeled by conventional methods was below 50%. These findings indicate the utility of microfluidic devices for automatic and rapid synthesis of high-quality RICs.

Deformable baffles coupled with pulsatile flow improve mixing in microfluidic devices

An important objective for many microfluidic mixer devices is to attain a high level of mixing efficiency at low Reynolds numbers. Previous research incorporating rigid obstacles into microchannels has shown enhanced chaotic advection and improved mixing index; however, the increased pressure drop and corresponding shear forces within the fluid domain can create issues in biological applications. In this paper, we show how an innovative micromixer strategy, i.e., incorporating deformable baffles and utilizing pulsatile flow, results in a high level of mixing efficiency at low Reynolds numbers (Re =1.25), where diffusion is the pure mechanism of mixing. The numerical investigation involved solving the continuity, Navier-Stokes, solid mechanics, and fluid-solid interaction equations alongside a convection-diffusion model to analyze species concentration. To find the best conditions of the micromixer, the mixing index as the objective function was optimized, and various parameters, including phase difference, velocity ratio, Strouhal number, baffle distance, and Reynolds number, were investigated. Through optimization of these parameters, we show a notable improvement in the mixing index (increase from 21.7 % to 78.86 %) at a Reynolds number of 1.25 with 2 mixing units, more than 92 % mixing efficiency by using 6 mixing units, and more than 95 % mixing efficiency at a Reynolds number of 0.1. Moreover, the incorporation of deformable baffles and pulsation results in a lower pressure drop. These conditions are optimal for biological applications that require thorough mixing of the sample inputs.

Maximizing Chlorobenzene Product Yield by Modifying The Benzene Chlorination Process

Chlorobenzene is extensively used in the manufacture of phenol, aniline, and DDT; as a solvent for paints; and as a heat transfer medium. It is also occasionally used in the dry-cleaning industry. With the many uses of chlorobenzene, its production must have high efficiency both in terms of energy and mass in order to obtain maximum profits. In this paper, we will explain how to maximize chlorobenzene product yield by modifying the benzene chlorination process. The process modification was carried out by adding one distillation column unit and one mixer unit. Meanwhile, to carry out sensitivity analysis, case study tools on chemical engineering software were used. Based on process modifications, an increase in chlorobenzene yield was obtained from 83% to 98%. The results of the case study indicate that the higher the benzene pressure entering the reactor, the lower the yield of the liquid product exiting the reactor. Meanwhile, the higher the ratio of benzene mass flow to chlorine gas mass flow, the higher the yield of the liquid product exiting the reactor. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A 30-60 GHz Broadband Low LO-Drive Down-Conversion Mixer with Active IF Balun in 65 nm CMOS Technology.

A 30~60 GHz broadband down-conversion mixer driven by low local oscillator (LO) power is presented. The down-conversion mixer utilizes an input signal coupling technique based on the Marchand balun to achieve broadband operation and achieves low LO power drive and low DC power consumption through the use of a weak inversion bias with Gilbert switching devices. The broadband conversion of single-ended to differential signals is achieved using the Marchand balun with compensation lines, and an equivalent circuit analysis is performed. For the intermediate frequency (IF) output, a self-biased IF trans-impedance amplifier with current reusing and an active IF balun structure are used to achieve signal amplification and single-ended signal output. Test results show that the proposed mixer achieves a conversion gain of -1.2 to 6.4 dB in an IF output bandwidth of 0.1 to 5 GHz at radio frequency (RF) input frequencies of 30 to 60 GHz and LO driving power of -10 dBm. The DC power consumption of the core mixing unit of the proposed mixer is 4.8 mW, and the DC power consumption including the IF amplifier is 28.3 mW. The proposed mixer uses a 65 nm CMOS technology with a chip area of 0.26 mm2.

ИЗУЧЕНИЕ ПРОЦЕССА СМЕШЕНИЯ ОСНОВНЫХ КОМПОНЕНТОВ АДСОРБИРУЮЩЕГО ГИГИЕНИЧЕСКОГО СРЕДСТВА

The results of research on the study of the mixing process to develop the basic composition of an adsorbent hygienic product for keeping animals and birds in accordance with sanitary standards are presented. The possibility of using a rotary ball mill as the most effective apparatus for grinding and mixing and a turbulent mixer, ensuring high homogeneity when mixing the main ingredients of mixtures, is investigated. In result of studying the processes of mixing the main ingredients in the preparation of an adsorbent hygiene product in various mixing units, an effective basic composition of an adsorbent hygiene product is obtained. Moreover, the components chalk M-5, attapulgite and synthetic amorphous silicon dioxide, obtained by mixing in a turbulent mixer and corresponding to the required specific surface area of 12000 cm2/g, which will provide the necessary sorption capacity and thereby ensure a reduction in pathogenic microflora in places where farm animals and poultry are kept. The developed basis of an adsorbent hygienic powder product, due to its significant specific surface area, will provide a high degree of moisture absorption and create the required level of sanitary and hygienic conditions for keeping animals and birds. Creating a favorable climate for keeping farm animals and poultry will significantly prevent the proliferation of bacteria, which will entail a significant reduction in the consumption of antibiotics when raising farm animals, reduce the level of unpleasant odors, and provide a dry environment for keeping animals and birds

The Choice of a Promising Design of a Fertilizer Mixing Unit Using Computer Simulation Technologies

The article deals with applying solid mineral fertilizers within the framework of the precision farming system. The use of complex mineral fertilizer compositions in the fields with an uneven demand for macroelements leads to the bigger amount of fertilizer applied, which has a detrimental effect on the ecology, the physical condition of the soil and the crop itself. It is proposed to use fertilizer mixtures the composition of which has been adjusted in fertilizer mixing units. The existing mixers have been analyzed, the processes occurring during operation of the screw, drum and centrifugal mixers were simulated. The results of the simulation showed that the unevenness coefficient kс for the drum-type mixer was 8.6%, for the blade-type mixer 17.3, and for the centrifugal mixer 3.5%.

Local analysis of micro mixing for the Villermaux-Dushman protocol by using the imaging UV-Vis spectroscopy

The Villermaux-Dushman protocol with UV-Vis analytics is an established tool to characterize the global micro mixing performance in process equipment. The local mixing process is described by a micro mixing model (incorporation model), originally designed for turbulent flows. The novel imaging UV-Vis spectroscopy used in this work uncovers locally resolved micro mixing phenomena in a laminar split-and-recombine (SAR) mixer unit manufactured from selective laser-induced etching (SLE). The local absorbance is recorded with a high spatial resolution camera through a telecentric lens and post-processed into local concentration fields of components. The method unveils discrepancies of the micro mixing time determined from the conventional incorporation model in laminar flow and the locally recorded mixing process. The micro mixing time rather needs to be seen as a mean micro mixing time instead. Furthermore, the spatial information obtained by the imaging UV-Vis spectroscopy gives insight into local micro mixing and selectivity, yielding new approaches to equipment optimization.

Development of a Mechanical System to Produce Animal Feed from Rice Straw

Rice straw stands out as the primary agricultural residue posing significant challenges for both farmers and the Egyptian government. Its volume accounts for approximately 18% of the total annual waste generated. Livestock farmers typically harvest the straw and feed it to their animals. However, the process of manually mixing molasses, urea, and salts with the straw often leads to inconsistent blending and uneven distribution of the mixture. This inconsistency poses a considerable risk to the health of the animals, potentially resulting in fatalities. Thus, a mechanical system for producing animal feed (rice straw cutting mixed with additives of urea, minerals and molasses) was developed. This system consists of a chopping unit, mixing unit, and pumping &amp;amp; distribution unit. Measurements included the uniformity of the cut rice straw pieces within the preferred size, the uniformity of the dissolved additives mixture and the uniformity of the additives distribution on cut rice straw. Crude protein and urea percentages were measured in the final product. The results showed a maximum production rate of 0.6 ton h-1 the suitability of the developed system for mixing the additives with the cut rice straw. The suitability of the developed system was determined through the uniformity of the distribution of the additives on the cut rice straw. The results showed that the optimum content of crude protein of 6.2% was found at urea content of 5% and a mixing unit shaft speed of 300 rpm and 5 min mixing time. Also, the developed system achieved a rate of return of 19% and a payback period of about two years.

Performance simulation of a dual-channel micro-mixer

In order to investigate whether changing the relative positions of the connecting units of a micro-mixer with dual connecting units would affect the mixing performance, the group proposed a micro-mixer with dual connecting units based on previous studies. The micro-mixer consists of a T-shaped inlet, six cubic mixing chambers and a dual connection channel between the mixing chambers. Numerical simulations showed that the outlet mixing index was 40.6% when the positions of the inlet and connecting units of the micro-mixer were staggered on both sides of the horizontal center and on both sides of the vertical center. At the same flow rate, the mixing index of the first mixing unit reaches 66.4% when the inlet of the micro-mixer changes from both sides of the horizontal center to a T-shaped inlet. The increase in the mixing index suggests that the contraction-stretching dual-channel arrangement can be utilized to promote mixing by utilizing the non-equilibrium vortices generated by the diffusion displacement limitations on the side walls of the mixing unit. The mixing efficiency of the optimized model designed according to this strategy increased to 85.8%. This paper provides a new perspective for optimizing the structural design and performance enhancement of micro-mixers.

Novel synthesis, characterization, and application of calcium ferrate (VI) in water treatment

Poor raw water quality has led science and technology research to explore more environmentally friendly water treatment methods, such as advanced oxidation processes. Ferrate (VI) salts have been regarded as a new green oxidant, cost-effective, and coagulant/flocculent in a single mixing and dosing unit in wastewater treatment. This research aimed to synthesize calcium ferrate (CaFeO4), a benign green chemical that can be utilized to treat water and wastewater through a facile wet oxidation process, with minimal increase in electrical conductivity. This study used the wet oxidation approach to synthesize stable aqueous calcium ferrate in an alkaline media using distilled water. During process optimization, CaFeO4 was synthesized and named 60-CaFeO4, 70-CaFeO4, 80-CaFeO4, and 90-CaFeO4, where the numbers represent the synthesis temperature. The prepared CaFeO4 was characterized using XRD, FT-IR, UV–Vis, TEM, SEM, Raman, and redox titration. FT-IR analysis confirmed the presence of the Fe–O stretching vibrations in all the freeze-dried CaFeO4 powders, signifying the successful preparation of the materials. The physicochemical characteristics of raw water, such as turbidity, color, COD, pH, EC, and TDS, were analyzed before and after treatment with CaFeO4. A jar test was performed to evaluate the reactivity and efficiency of the CaFeO4 toward wastewater treatment through coagulation/flocculation processes. After coagulation using CaFeO4, the pollutants levels were reduced COD (43.56–71.56%) and turbidity (97–99%), signifying the effectiveness of the as-prepared materials. CaFeO4 was successfully produced at various temperatures and was stable enough to be stored at room temperature for over six months without significantly decomposing.Graphical abstract

ЭНЕРГОСБЕРЕГАЮЩИЙ СМЕСИТЕЛЬ ДЛЯ ПРИГОТОВЛЕНИЯ СУХИХ СТРОИТЕЛЬНЫХ СМЕСЕЙ

The article describes an experimental installation of an energy-saving mixing unit for the preparation of dry building mixes. The installation consists of a receiving device for loading various components, a mixing chamber, which includes two shafts with blades that allow to intensify the process of movement of the components of the mixture, and thereby reduce the time for mixing them. The shafts are driven by two electric motors, a valve is provided for unloading the finished mixture, installed in the lower part of the mixing chamber, which is controlled by a pneumatic system for quick operation. The article presents the results of experimental studies to establish the influence of the structural and technological parameters of the mixer: the angle of inclination of the blades, the circumferential speed of their rotation and the mixing time on the qualitative characteristics of the mixing process of dry building mixes. It was found that an increase in the angle of inclination of the blades leads to an increase in the power spent on the mixing process of the components. This is due to the fact that with an increase in the angle of inclination of the blade, it is accompanied by an increase in the resistance to mixing, as the area of its contact with the mixture increases. An increase in the rotation frequency of the rotors entails a proportional increase in power. With an angle of inclination of the blades equal to 45 ° to the direction of its movement, the best result of preparing the mixture is achieved.

Modernization of local heat distribution stations of city heat supply system

The PURPOSE of this work is to develop technical solutions to increase the efficiency of functioning of centralized urban heating systems by modernizing local heat distribution stations. The article considers the issues of functioning of district heating systems with open water intake. The work presents technical solutions that increase the efficiency of the local heat distribution station with a hot water supply unit. A technological scheme has been developed, the selection of equipment has been made. The feasibility of using the developed technical solutions is confirmed by technical, economic and investment indicators. The objectivity of determining the technical and economic effect of the modernization of the local heat distribution station is ensured by comparing the obtained indicators of the modernized and similar facilities.METHODS. To fulfill the objectives of the study, the following methods were applied: full-scale tests on a real object; processing of experimental data using application programs; feasibility study in the municipal heat power industry.THE RESULTS show an improvement in the technical and economic performance of the heating and hot water supply system of an apartment building in Yoshkar-Ola city: reduced network water consumption by 36–39%; temperature drop in the return pipeline was 13.5%; the heat content of hot water has been reduced to 0.168 Gcal/m3 (normative heat content is 0.145 Gcal/m3), the required circulation was ensured in all risers of the hot water supply system. The total losses from October 2021 to September 2022 are 3486,4 Gcal or 11.4% of heat supplied to consumers, which is less than 13% set by the tariff. Compared to a similar house without a regulation depending on the outside air temperature, the consumption of thermal energy during the heating season is reduced by 80 Gcal (10.9%).CONCLUSION. The new scheme of a local heat distribution station has been proposed, including the regulation of domestic hot water (DHW) recirculation, as well as the installation of a hydroelevator with weather regulation. The developed technical solution is relevant for district heating systems with open water intake. For the first time, an experimental study of the effect of the joint installation of the following equipment was carried out: a pump and a control valve on the DHW recirculation line before the recirculation mixing unit with the return pipeline of the heating system; hydraulic elevator with weather regulation. The results of the study can be used in the feasibility study of similar circuit solutions for the modernization of DHW systems. Operating experience has shown that the application of the developed technological scheme of local heat distribution station has positive effects: reduction of network water consumption, temperature in the return pipeline and heat losses; improvement of circulation in all risers of the DHW system; reduction of thermal energy consumption during the period of the “lower” cutoff of the temperature graph; curbing the growth of tariffs for thermal energy.

Mixing Performance Analysis of Cohesive Granular Particles in a Planetary Concrete Mixer Containing Two Different Mixing Units via DEM

In this paper, the mixing behavior of two different types of planetary concrete mixers is analyzed and evaluated in terms of homogeneity and granular particle velocity flow regimes. For this, the Hertz-Mindlin contact law, constant directional torque, and Simplified Johnson-Kendall-Roberts (SJKR) models are utilized via the Discrete Element Method (DEM). The Lacey mixing index was employed to calculate the mixing degree of granular particles to assess the mixing performance of planetary concrete mixers. Comparing the mixing degree, we have achieved a 45,5% improvement in the mixing period of high-quality homogeneous mixture in the model B mixer.

Low tar yield and high energy conversion efficiency in a continuous pyrolysis reactor with modified ribbon screw conveyor

The high temperature batch and continuous pyrolysis of rice husk, sewage sludge, composite waste, hazelnut and apricot kernel shell were performed at 850 °C in a rotating batch reactor and a continuous reactor with a modified ribbon screw conveyor. Batch results were used in the continuous reactor design and comparison. At the continuous pyrolysis experiments, mixing and conveying efficiency of screw and thermal cracking performance of reactor, heated gas line and cyclone were investigated. Each material was fed into the reactor continuously with a feed rate of 4.5 kg/h for 3.5 h, and then the pipelines and reactor were monitored and collected tar and char were analyzed. The mixing unit and uninterrupted heated system showed excellent performance on tar reduction and tar yields were lower than 1.7 % for all materials. Separation of char dust from the gas without tar condensation in a heated cyclone prevented blocking in gas lines. With the secondary reactions syngas energy conversion efficiency for rice husk, sewage sludge, composite waste, hazelnut shell, and apricot kernel shell were 67.76 %, 59.22 %, 76.35 %, 56.96 %, 61.98 % respectively. With the new design with a modified ribbon screw, different types of materials were decomposed with minimum char yield in less than 15 min without mechanical problems. The high capacity of the installed reactor as 1–10 kg/h moved the technology readiness level (TRL) to 5 and set an example for demonstration in operational environment.

Влияние регенерации слоистого модификатора трения на триботехнические свойства смазочных композиций

The paper examines an influence of the regeneration efficiency of the developed anti-wear additive on tribological properties of the lubricating composition, including a lubricating oil and the additive. The anti-wear additive was a layered friction modifier – molybdenum diselenide MoSe2, mixed in the volume of a composition of unsaturated fatty acids – stearic acid and oleic acid. Lubricating oil M-16G2TSS was chosen as the base lubricant, with respect to which the tribological properties of other lubricants submitted for testing are compared. For all cycles of tests, a volume of no more than 25 cm3 of lubricant was used to avoid high thermal inertia when the test samples moved on the friction machine. Experiments of the regeneration of the additive were carried out on a rotary mixing unit of the author's design, and the solution has a long storage period of 8 640 hours (about 12 calendar months). The possibility of restoring the uniform distribution of molybdenum diselenide throughout the volume of the additive in a suspended state has been revealed. This lubricant composition, after restoration of the structure by stirring, can be used in the production of a lubricant composition based on M-16G2TSS oil. Using a reciprocating friction unit of a friction machine, simulating the cylinder-piston group of a marine diesel engine, the resulting lubricant composition was compared with other lubricants based on molybdenum diselenide, the additive solutions of which have different storage periods before being added to the lubricating oil, as well as with the base lubricating oil. The assessment of the tribological properties of lubricants based on M-16G2TSS oil by determining the weight wear and further using this value to estimate the resource of the friction unit has been made. Rotational regeneration has shown satisfactory effectiveness in partially restoring of the tribological properties of a lubricant composition with the participation of an additive, but is not enough effective compared to rotational pulsation mixing of the additive in order to create perspective lubricant compositions.

Kinetically Controlled Nucleation Enabled by Tunable Microfluidic Mixing for the Synthesis of Dendritic Au@Pt Core/Shell Nanomaterials.

The nucleation stage plays a decisive role in determining nanocrystal morphology and properties; hence, the ability to regulate nucleation is critical for achieving high-level control. Herein, glass microfluidic chips with S-shaped mixing units are designed for the synthesis of Au@Pt core/shell materials. The use of hydrodynamics to tune the nucleation kinetics is explored by varying the number of mixing units. Dendritic Au@Pt core/shell nanomaterials are controllably synthesized and a formation mechanism is proposed. As-synthesized Au@Pt exhibited excellent ethanol oxidation activity under alkaline conditions (8.4 times that of commercial Pt/C). This approach is also successfully applied to the synthesize of Au@Pd core/shell nanomaterials, thus demonstrating its generality.