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Conversion of polyethylene to gasoline: Influence of porosity and acidity of zeolites

《能源前沿（英文）》 2023年 第17卷 第6期   页码 763-774 doi: 10.1007/s11708-023-0897-1

摘要： Plastic waste is causing serious environmental problems. Developing efficient, cheap and stable catalytic routes to convert plastic waste into valuable products is of great importance for sustainable development, but remains to be a challenging task. Zeolites are cheap and stable, but they are usually not efficient for plastic conversion at a low temperature. Herein a series of microporous and mesoporous zeolites were used to study the influence of porosity and acidity of zeolite on catalytic activity for plastics conversion. It was observed that H-Beta zeolite was an efficient catalyst for cracking high-density polyethylene to gasoline at 240 °C, and the products were almost C4–C12 alkanes. The effect of porosity and acidity on catalytic performance of zeolites was evaluated, which clearly visualized the good performance of H-Beta due to high surface area, large channel system, large amount accessible acidic sites. This study provides very useful information for designing zeolites for efficient conversion of plastics.

关键词： plastics conversion     polyethylene     zeolites     acidity     porosity    

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A time−space porosity computational model for concrete under sulfate attack

《结构与土木工程前沿（英文）》 2023年 第17卷 第10期   页码 1571-1584 doi: 10.1007/s11709-023-0985-7

摘要： The deterioration of the microscopic pore structure of concrete under external sulfate attack (ESA) is a primary cause of degradation. Nevertheless, little effort has been invested in exploring the temporal and spatial development of the porosity of concrete under ESA. This study proposes a mechanical–chemical model to simulate the spatiotemporal distribution of the porosity. A relationship between the corrosion damage and amount of ettringite is proposed based on the theory of volume expansion. In addition, the expansion strain at the macro-scale is obtained using a stress analysis model of composite concentric sphere elements and the micromechanical mean-field approach. Finally, considering the influence of corrosion damage and cement hydration on the diffusion of sulfate ions, the expansion deformation and porosity space−time distribution are obtained using the finite difference method. The results demonstrate that the expansion strains calculated using the suggested model agree well with previously reported experimental results. Moreover, the tricalcium aluminate concentration, initial elastic modulus of cement paste, corrosion damage, and continuous hydration of cement significantly affect concrete under ESA. The proposed model can forecast and assess the porosity of concrete covers and provide a credible approach for determining the residual life of concrete structures under ESA.

关键词： expansion deformation     porosity     internal expansion stress     external sulfate attack     mechanical–chemical coupling model    

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Tuning porosity of coal-derived activated carbons for CO2 adsorption

《化学科学与工程前沿（英文）》 2022年 第16卷 第9期   页码 1345-1354 doi: 10.1007/s11705-022-2155-1

摘要： A simple method was developed to tune the porosity of coal-derived activated carbons, which provided a model adsorbent system to investigate the volumetric CO2 adsorption performance. Specifically, the method involved the variation of the activation temperature in a K2CO3 induced chemical activation process which could yield activated carbons with defined microporous (< 2 nm, including ultra-microporous < 1 nm) and meso-micro-porous structures. CO2 adsorption isotherms revealed that the microporous activated carbon has the highest measured CO2 adsorption capacity (6.0 mmol∙g–1 at 0 °C and 4.1 mmol∙g–1 at 25 °C), whilst ultra-microporous activated carbon with a high packing density exhibited the highest normalized capacity with respect to packing volume (1.8 mmol∙cm−3 at 0 °C and 1.3 mmol∙cm–3 at 25 °C), which is significant. Both experimental correlation analysis and molecular dynamics simulation demonstrated that (i) volumetric CO2 adsorption capacity is directly proportional to the ultra-micropore volume, and (ii) an increase in micropore sizes is beneficial to improve the volumetric capacity, but may lead a low CO2 adsorption density and thus low pore space utilization efficiency. The adsorption experiments on the activated carbons established the criterion for designing CO2 adsorbents with high volumetric adsorption capacity.

关键词： coal-derived activated carbons     porosity     CO2 adsorption     molecular dynamics    

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Experimental studies on the influence of porosity on membrane absorption process

GAO Jian, REN Zhongqi, ZHANG Zeting, ZHANG Weidong

《化学科学与工程前沿（英文）》 2007年 第1卷 第4期   页码 385-389 doi: 10.1007/s11705-007-0070-0

摘要： Eight kinds of flat membranes with different micro-structures were chosen to carry out the membrane absorption experiments with CO and de-ionized water or 0.1 mol · L NaOH solution as the experimental system. According to experimental results, the membrane pores shape (stretched pore and cylinder pore) and membrane thickness do not affect the membrane absorption process, and the membrane porosity has only little influence on membrane absorption process for slow mass transfer system. However, the influence of porosity on the membrane absorption process became visible for fast mass transfer system. Moreover, the mass transfer behavior near the membrane surface on liquid side was studied. The results show that the influence of membrane porosity on mass transfer relates to flow condition, absorption system and distance between micro-pores, etc.

关键词： de-ionized     · L     different     membrane porosity     CO    

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Easily-manufactured paper-based materials with high porosity for adsorption/separation applications in

《化学科学与工程前沿（英文）》 2023年 第17卷 第7期   页码 830-839 doi: 10.1007/s11705-022-2267-7

摘要： A multi-functional porous paper-based material was prepared from grass pulp by simple pore-forming and green cross-linking method. As a pore-forming agent, calcium citrate increased the porosity of the paper-based material from 30% to 69% while retaining the mechanical strength. The covalent cross-linking of citric acid between cellulose fibers improved both the wet strength and adsorption capacity. In addition, owing to the introduction of high-content carboxyl groups as well as the construction of hierarchical micro-nano structure, the underwater oil contact angle was up to 165°. The separation efficiency of the emulsified oil was 99.3%, and the water flux was up to 2020 L·m–2·h–1. The theoretical maximum adsorption capacities of cadmium ion, lead ion and methylene blue reached 136, 229 and 128.9 mg·g–1, respectively. The continuous purification of complex wastewater can be achieved by using paper-based materials combined with filtration technology. This work provides a simple, low cost and environmental approach for the treatment of complex wastewater containing insoluble oil, organic dyes, and heavy metal ions.

关键词： adsorption     oil–water separation     underwater superoleophobicity     wastewater treatment    

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The ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of

《结构与土木工程前沿（英文）》 2022年 第16卷 第2期   页码 191-201 doi: 10.1007/s11709-021-0792-y

摘要： A new insight into the interfacial transition zone (ITZ) in cement mortar specimens (CMSs) that is influenced by cement fineness is reported. The importance of cement fineness in ITZ characterizations such as morphology and thickness is elucidated by backscattered electron images and by consequences to the compressive (Fc) and flexural strength (Ff), and porosity at various water/cement ratios. The findings indicate that by increasing the cement fineness the calcium silicate hydrate formation in the ITZ is favored and that this can refine the pore structures and create a denser and more homogeneous microstructure. By increasing cement fineness by about 25% of, the ITZ thickness of CMSs was reduced by about 30% and Fc was increased by 7%–52% and Ff by 19%–40%. These findings illustrate that the influence of ITZ features on the mechanical strength of CMSs is mostly related to the cement fineness and ITZ microstructure.

关键词： cement fineness     interfacial transition zone     compressive and flexural strength    

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Effect of process parameters on the density and porosity of laser melted AlSi10Mg/SiC metal matrix composite

Omotoyosi H. FAMODIMU, Mark STANFORD, Chike F. ODUOZA, Lijuan ZHANG

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 520-527 doi: 10.1007/s11465-018-0521-y

摘要：

Laser melting of aluminium alloy—AlSi10Mg has increasingly been used to create specialised products in various industrial applications, however, research on utilising laser melting of aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus, an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of aluminium metal matrix composites. The effects of several parameters of the laser melting process on the mechanical blended composite were thus investigated in this research. This included single track formations of the matrix alloy and the composite alloyed with 5% and 10% respectively for their reaction to laser melting and the fabrication of density blocks to investigate the relative density and porosity over different scan speeds. The results from these experiments were utilised in determining a process window in fabricating near-fully dense parts.

关键词： selective laser melting     additive manufacturing     mechanical alloying     powder metallurgy     aluminium metal matrix composite    

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我国低孔渗储层天然气资源大型化成藏特征与分布规律

赵文智,王红军,卞从胜,汪泽成,柳广弟

《中国工程科学》 2012年 第14卷 第6期   页码 31-39

摘要：

低孔渗储层天然气资源是目前和未来一段时间我国天然气勘探和开发的主体，具有大型化成藏的特点。集中讨论了这类天然气资源大型化成藏的特征和分布规律，认识到成藏要素具有大型化发育与规模变化的特征，是天然气大型化成藏的基础；薄饼式、集群式成藏是天然气大型化成藏的主要样式；气源灶埋藏期规模“蓄能”和抬升期规模排气是大型化成藏重要气源输入；体积流和扩散流充注是天然气大型化成藏的主要运聚方式。低孔渗储层天然气藏的成藏分布具有近源性，成藏组合以大面积和大范围两种类型为主，成藏类型以地层—岩性圈闭为主，主要分布在海相克拉通盆地古隆起围斜区、陆内坳陷盆地广大斜坡区和向斜区以及前陆盆地缓翼斜坡等地区。低孔渗储层天然气资源大型化成藏认识的提出，提升了我国天然气资源发现潜力，扩展了勘探范围，为客观评价我国天然气主体资源总量和分布、推动有效发现大气田提供了理论基础。

关键词： 低孔渗储层     大型化成藏     体积流     扩散流     薄饼式     集群式    

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Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 11-23 doi: 10.1007/s11709-010-0081-7

摘要： Macroscopic modeling of soils is based on a number of properties that refer to the mesoscopic morphology. The most fundamental parameters of this art are: 1) coupling parameters between partial stresses of components and deformations of components, 2) porosities, 3) saturation, and 4) permeability and diffusivity, tortuosity. The main aim of this paper is to present in juxtaposition continuous one-, two-, and three-component models of geomaterials appearing in construction of embankment dams. In particular, the above mentioned features, especially saturation with water and seepage problems, modeling of fluidization yielding piping, and generalizations of the Darcy law and changes of porosity, are presented.

关键词： thermomechanical modeling     soil morphology     saturation     porosity    

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堆积床相变储热系统中径向孔隙率振荡分布对热性能的影响 Article

刘红兵, 赵长颖

《工程（英文）》 2021年 第7卷 第4期   页码 515-525 doi: 10.1016/j.eng.2020.05.020

摘要：

由于具有较高的储热能力和传热速率，堆积床相变储热被认为是一种很有潜力的储热方法。在堆积床中，壁面效应会影响相变胶囊的填充结构，从而引起径向孔隙率的振荡。本研究建立了一个基于球体实际堆积过程的三维堆积床相变储热模型，以描述径向孔隙率的振荡分布，并分析了其内部的流动和传热情况。通过在堆积床中沿径向不同位置截取圆柱面，揭示了相变胶囊的排列与径向孔隙率之间的对应关系。径向孔隙率的振荡分布导致换热流体速度呈不均匀分布，因此相变材料的径向温度分布和液相分数分布进一步受到影响。此外，本文讨论了不同的无量纲参数（如管与胶囊的直径比、雷诺数和史蒂芬数）对换热流体和相变材料径向特性的影响。结果表明，不同的直径比对应于不同的径向孔隙率分布。此外，随着直径比的增加，在壁面附近区域换热流体速度显著变化，而中心区域换热流体速度的不均匀性将减小。雷诺数和史蒂芬数对换热流体的相对速度分布有轻微影响，而更高的雷诺数可导致速度成比例地提高，史蒂芬数的增加可加快堆积床相变储热系统的储热过程。

关键词： 堆积床相变储热     径向孔隙率振荡     流动换热     传热强化     直径比    

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Porosity model for flows in CMP

ZHANG Chao-hui, YE Wei, LUO Jian-bin, WEN Shi-zhu

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 418-423 doi: 10.1007/s11465-006-0050-y

摘要： In an effort to explore the contribution of the pad, which is usually full of pores, to the performance of CMP (chemical mechanical polishing), a three-dimensional flow model of CMP is presented by assuming that the fluids in the porous layer comply with Darcy s law, which states that the flow velocity is proportional to the pressure gradient and inverse proportional to the viscosity. The flow equation is deduced accordingly and, by taking advantage of the multilevel technique and line relaxation technique, numerical simulations are carried out to reveal the relationships between the load capacities and operational parameters (including pivot height, roll angle and pitch angle), under conditions with different porous parameters and different thicknesses of the porous layer. The little porous parameter will lead to a prominent increase of load capability (for instance, the load and the moment predicted), which is still augmented by the thicker layer parameter. This will result in a higher material removal ratio of CMP. A pad full of large pores will be used to deduce load capability, facilitating the free flow of the fluids through the pores. The research will add some insights on the mechanism of the CMP technique.

关键词： multilevel technique     three-dimensional     proportional     research     thicker    

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Directional solidification of metal-gas eutectic and fabrication of regular porous metals

LIU Yuan, LI Yanxiang, WAN Jiang

《机械工程前沿（英文）》 2007年 第2卷 第2期   页码 180-183 doi: 10.1007/s11465-007-0030-x

摘要： Directional solidification of metal-gas eutectic (Gasar) is a novel process for making regular porous metals. This process is based on a solid-gas eutectic reaction involving a gaseous medium and a metal or ceramic phase. The process easily controls the porosity, the pore size, the pore orientation, and the pore morphology when the melting and solidifying conditions are varied in a wide range. The latest progress and our research work are reviewed in this paper.

关键词： orientation     solid-gas eutectic     research     solidifying     porosity    

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Pore structure of cementitious material enhanced by graphitic nanomaterial: a critical review

S.A. GHAHARI, E. GHAFARI, L. ASSI

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 137-147 doi: 10.1007/s11709-017-0431-9

摘要： Carbon nano tubes (CNT) has been introduced as an efficient nanomaterial in order to improve the mechanical and durability properties of concrete. The effect of CNT on the microstructures of cementitious materials has been widely reported. This paper combines a critical review on the effect of CNT on the pore and microstructure of cement composite with a discussion on the porosity measurement of pastes containing CNT using mercury intrusion porosimetry techniques (MIP). It was found that, surface treatment by H SO and HNO solution forms carboxyl acid groups on CNTs’ surfaces that lead to the improvement of reinforcement. In this scope, this review paper involves analyzing the effect of CNT on the microstructure and the pore structure of cementitious materials. The existing methods of measuring the porosity of cementitious material are reviewed, in particular, the contact angle measurement is discussed in detail in which the most effective parameters and possible errors of calculation is presented.

关键词： carbon nano tubes     microstructure     porosity     mercury intrusion porosimetry     cement composite    

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Industrial bio-based plant aggregates as hygric and insulating construction materials for energy efficient building

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

《化学科学与工程前沿（英文）》 2022年 第16卷 第10期   页码 1532-1532 doi: 10.1007/s11705-020-1960-7

摘要： In this paper, the bulk density, microstructure, porosity and pore size distribution of the selected aggregates, including hemp shiv, flax shiv, rape shiv and wheat straw, are fully studied due to these properties are highly related to their excellent characteristics and more or less linked to the properties of the final product. The scanning electron microscope results showed all the selected aggregates have a highly porous and complex hierarchical structure, whereas the arrangement of pores and the thickness of cell wall are significantly different among these aggregates. All the selected aggregates had a low bulk density ranging from 30 to 130 kg∙m and a high porosity between 75.81% and 88.74%. The thermal conductivity of the selected bio-aggregates ranged from 0.04 to 0.06 W∙m ∙K . The thermal conductivity of the selected aggregates was not only depending on the bulk density of the sample but also depending on the raw material. Hemp shiv, rape shiv and flax shiv were excellent hygric regulators with moisture buffer value ( ) ranging from 2.07 to 2.36 g∙m ∙%RH , whereas, wheat straw had a lower MBV value ranging from 1.76 to 1.97 g∙m ∙%RH . The results showed that particle size does not affect the value. The value increases linearly with bulk density.

关键词： bio-based aggregates     density     porosity     thermal conductivity     hygric properties    

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核磁共振在石油测井与地层油气评价中的应用

肖立志,谢然红

《中国工程科学》 2003年 第5卷 第9期   页码 87-94

摘要：

核磁共振（NMR）在石油测井和地层油气评价中已经得到应用，是当前地球物理勘探的前沿领域之一。介绍了NMR测井的测量原理、应用基础和地层信息的表达方式，并讨论了NMR测井的主要应用和实例。

关键词： 核磁共振     测井     地层评价     孔隙度     束缚水     渗透率    

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标题 作者 时间 类型 操作

Conversion of polyethylene to gasoline: Influence of porosity and acidity of zeolites

期刊论文

A time−space porosity computational model for concrete under sulfate attack

期刊论文

Tuning porosity of coal-derived activated carbons for CO2 adsorption

期刊论文

Experimental studies on the influence of porosity on membrane absorption process

GAO Jian, REN Zhongqi, ZHANG Zeting, ZHANG Weidong

期刊论文

Easily-manufactured paper-based materials with high porosity for adsorption/separation applications in

期刊论文

The ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of

期刊论文

Effect of process parameters on the density and porosity of laser melted AlSi10Mg/SiC metal matrix composite

Omotoyosi H. FAMODIMU, Mark STANFORD, Chike F. ODUOZA, Lijuan ZHANG

期刊论文

我国低孔渗储层天然气资源大型化成藏特征与分布规律

赵文智,王红军,卞从胜,汪泽成,柳广弟

期刊论文

Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

期刊论文

堆积床相变储热系统中径向孔隙率振荡分布对热性能的影响

刘红兵, 赵长颖

期刊论文

Porosity model for flows in CMP

ZHANG Chao-hui, YE Wei, LUO Jian-bin, WEN Shi-zhu

期刊论文

Directional solidification of metal-gas eutectic and fabrication of regular porous metals

LIU Yuan, LI Yanxiang, WAN Jiang

期刊论文

Pore structure of cementitious material enhanced by graphitic nanomaterial: a critical review

S.A. GHAHARI, E. GHAFARI, L. ASSI

期刊论文

Industrial bio-based plant aggregates as hygric and insulating construction materials for energy efficient building

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

期刊论文

核磁共振在石油测井与地层油气评价中的应用

肖立志,谢然红

期刊论文