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1.
《International Journal of Hydrogen Energy》2022,47(79):33765-33780
This work investigates selective Ni locations over Ni/CeZrOx–Al2O3 catalysts at different Ni loading contents and their influences on reaction pathways in ethanol steam reforming (ESR). Depending on the Ni loading contents, the added Ni selectively interacts with CeZrOx–Al2O3, resulting in the stepwise locations of Ni over CeZrOx–Al2O3. This behavior induces a remarkable difference in hydrogen production and coke formation in ESR. The selective interaction between Ni and CeZrOx for 10-wt.% Ni generates more oxygen vacancies in the CeZrOx lattice. The Ni sites near the oxygen vacancies enhance reforming via steam activation, resulting in the highest hydrogen production rate of 1863.0 μmol/gcat·min. In contrast, for 15 and 20-wt.% Ni, excessive Ni is additionally deposited on Al2O3 after the saturation of Ni–CeZrOx interactions. These Ni sites on Al2O3 accelerate coking from the ethylene produced on the acidic sites, resulting in a high coke amount of 19.1 mgc/gcat·h (20Ni/CZ-Al). 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(6):3587-3610
Hydrogen is currently receiving significant attention as an alternative energy resource, and among the various methods for producing hydrogen, methanol steam reforming (MSR) has attracted great attention because of its economy and practicality. Because the MSR reaction is inherently activated over catalytic materials, studies have focused on the development of noble metal-based catalysts and the improvement of existing catalysts with respect to performance and stability. However, less attention has been paid to the modification and development of innovative MSR reactors to improve their performance and efficiency. Therefore, in this review paper, we summarize the trends in the development of MSR reactor systems, including microreactors and membrane reactors, as well as the various structured catalyst materials appropriate for application in complex reactors. In addition, other engineering approaches to achieve highly efficient MSR reactors for the production of hydrogen are discussed. 相似文献
3.
The current article focuses on mass and thermal transfer analysis of a two-dimensional immovable combined convective nanofluid flow including motile microorganisms with temperature-dependent viscosity on top of a vertical plate through a porous medium, and a model has been developed to visualize the velocity slip impacts on a nonlinear partial symbiotic flow. The governed equations include all of the above physical conditions, and suitable nondimensional transfigurations are utilized to transfer the governed conservative equations to a nonlinear system of differential equations and obtain numerical solutions by using the Shooting method. Numerical studies have been focusing on the effects of intricate dimensionless parameters, namely, the Casson fluid parameter, Brownian motion parameter, thermophoresis parameter, Peclet number, bioconvection parameter, and Rayleigh number, which have all been studied on various profiles such as momentum, thermal, concentration, and density of microorganisms. The concentration boundary layer thickness and density of microorganisms increased as the Casson fluid parameter, Brownian and thermophoresis parameters increased, whereas the bioconvection parameter, Peclet number, and Rayleigh number increased. The thermal boundary layer thickness, concentration boundary layer thickness, and density of microorganisms all decreased. The velocity distribution decreases as the Peclet number, bioconvection, and thermophoresis parameters rise but rises as the Rayleigh number, Brownian motion parameter, and Casson fluid parameter rise. These are graphed via plots along with divergent fluid parameters. 相似文献
4.
5.
介绍机械制造厂燃煤锅炉的烟尘特点,分析滤料失效的原因,提出一套针对该工况的滤料解决方案。介绍针对复杂工况条件所选用的纤维种类以及复合面层原料成分配比的确定,最终选用针刺工艺加工并对该新产品的基本性能进行了测试分析。 相似文献
6.
Kamalesh Pal Amitava Mukherjee Md. Motin Seikh Parthasarathi Bera Arup Gayen 《Ceramics International》2021,47(10):14798-14808
Synthesis of nanocrystalline pristine and Mn-doped calcium copper titanate quadruple perovskites, CaCu3?xMnxTi4?xMnxO12 (x = 0, 0.5, and 1.0) by modified citrate solution combustion method has been reported. Powder X-ray diffraction patterns attest the phase purity of the perovskite materials. Average particle sizes of all the materials obtained from the Scherrer's formula are in the range of 55–70 nm. The specific surface areas for all the perovskites obtained from BET isotherms are found to be low as expected for the condensed oxide systems and fall in the range of 13–17 m2 g?1. Transmission electron microscopy studies show a reduction in particle size of CaCu3Ti4O12 with increase in Mn doping. Ca and Ti are present in +2 and +4 oxidation states in all the materials as demonstrated by X-ray photoelectron spectroscopy analyses. Cu2+ gets reduced in CaCu3Ti4O12 with higher Mn content. Mn is observed to be present only in +3 oxidation state. All the materials have been examined to be active in CO oxidation as well as H2 production from methanol steam reforming. CaCu3Ti4O12 with ~14 at.% Mn is found to show best catalytic activities among these materials. A comprehensive analysis of the catalytic activities of these perovskites toward CO oxidation and H2 production from MSR reveal the cooperative activity of copper-manganese in the doped perovskites and it is more effective at lower manganese content. 相似文献
7.
Novel core-shell-like Ni-supported hierarchical beta zeolite catalysts on bioethanol steam reforming
《International Journal of Hydrogen Energy》2020,45(33):16409-16420
Hierarchical-Beta zeolites have been hydrothermally synthesized by adding a new gemini organic surfactant. The used gemini surfactant play the role of a “pore-forming agents” on the mesoscale, on the same time, providing alkaline environment for the system. With this hierarchical Beta zeolite as the core support, we successfully prepared a shell layer of Ni-containing (22 wt%) petal-like core-shell-like catalyst and applied it to bioethanol steam reforming. At the reaction temperature of 350 °C–550 °C, the conversion rate of ethanol and the selectivity of hydrogen were always above 85% and 70%. After reaction of 100 h on stream at 400 °C, there were not obvious inactivation could be observed on NiNPs/OH-MBeta catalyst. 相似文献
8.
《International Journal of Hydrogen Energy》2020,45(29):14790-14805
A novel multichannel reactor with a bifurcation inlet manifold, a rectangular outlet manifold, and sixteen parallel minichannels with commercial CuO/ZnO/Al2O3 catalyst for methanol steam reforming was numerically investigated in this paper. A three-dimensional numerical model was established to study the heat and mass transfer characteristics as well as the chemical reaction rates. The numerical model adopted the triple rate kinetic model of methanol steam reforming which can accurately calculate the consumption and generation of each species in the reactor. The effects of steam to carbon molar ratio, weight hourly space velocity, operating temperature and catalyst layer thickness on the methanol steam reforming performance were evaluated and discussed. The distributions of temperature, velocity, species concentration, and reaction rates in the reactor were obtained and analyzed to explain the mechanisms of different effects. It is suggested that the operating temperature of 548 K, steam to carbon ratio of 1.3, and weight hourly space velocity of 0.67 h−1 are recommended operating conditions for methanol steam reforming by the novel multichannel reactor with catalyst fully packed in the parallel minichannels. 相似文献
9.
以2,6-二甲基苯胺为原料,通过重氮化反应制备2,6-二甲基苯腈,经水蒸汽蒸馏法提纯后,采用75%硫酸酸化,再经酸碱法对产物进行脱色和纯化得产物2,6-二甲基苯甲酸,总收率68.4%。工艺简单、操作安全、适合工业化生产。 相似文献
10.
针对国内某炼油厂延迟焦化加热炉三点注汽问题,采用热负荷自动调节的算法进行了研究。运用该模型方法,分析了三点注汽量对加热炉热负荷和炉管结焦系数的影响,发现三点注汽量的改变均会对热负荷和炉管结焦系数产生影响,主要表现为提高注汽量将会提高热负荷,同时降低结焦系数;第1点注汽量和第2点注汽量对热负荷和结焦系数的影响较强,第3点注汽量对热负荷和结焦系数的影响较弱。在实际操作中,加热炉中的结焦程度既不能太强也不能太弱,合适的结焦系数能够保证正常开工周期里炉管不结焦,也能保证瓦斯、注汽量等参数的合理分配。通过对热负荷、注汽量的智能分配,可得到不同原料油加工负荷条件下更加合理的装置运行方案。 相似文献