scholarly journals Effect of Benzyltrimethylammonium Ion as a Co-directing Agent on Phase Transitions in a Nanostructure Silica/Surfactant Composite

2010 ◽  
Vol 7 (4) ◽  
pp. 1407-1411 ◽  
Author(s):  
Alireza Badiei ◽  
Hassan Goldooz ◽  
Ghodsi Mohammadi Ziarani
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Phase Transitions ◽  
Pore Size Distribution ◽  
Surface Charge ◽  
Pore Size ◽  
Size Distribution ◽  
Elemental Analysis ◽  
Constant Ph

Effect of benzyltrimethylammonium ion as a co directing agent in phase transition from hexagonal to cubic and lamellar mesophases was studied in the constant pH at 130 °C. This phase transformation was carried out in constant surface charge and pore size distribution (2 nm). Influence of BTMA+ions between head and tail of surfactant and phase transformation were observed by using the XRD and elemental analysis.

Effect of Pore-Size Distribution on Phase Transition of Hydrocarbon Mixtures in Nanoporous Media

SPE Journal ◽  
2016 ◽  
Vol 21 (06) ◽  
pp. 1981-1995 ◽  
Author(s):  
Lei Wang ◽  
Xiaolong Yin ◽  
Keith B. Neeves ◽  
Erdal Ozkan
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
Pore Size Distribution ◽  
Phase Behavior ◽  
Pore Size ◽  
Capillary Pressure ◽  
Size Distribution ◽  
Hydrocarbon Mixtures ◽  
Nanoporous Media ◽  
Light Oil

Summary Pore sizes of many shale-oil and tight gas reservoirs are in the range of nanometers. In these pores, capillary pressure and surface forces can make the phase behavior of hydrocarbon mixtures different from that characterized in pressure/volume/temperature (PVT) cells. Many existing phase-behavior models use a single pore size to describe the effect of confinement on phase behavior. To follow up with our earlier theoretical studies and experimental observations, this research investigates the effect of pore-size distribution. By use of a vapor/liquid equilibrium model that considers the effect of capillary pressure, we present a procedure to simulate the sequence of phase changes in a porous medium caused by a pore-size distribution. This procedure is used to simulate depressurizations of a light oil and a retrograde gas confined inside nanoporous media, the pore-size distributions of which are characteristic of tight reservoirs. The fluid compositions are representative of typical reservoir fluids. Predictions of the model show that phase transition in nanoporous medium with pore-size distribution is not described by a single phase boundary. The initial phase change in the large pores alters the composition of the remaining fluid, and, in turn, suppresses the next phase change. For the two cases studied, models with and without capillary pressure gave similar predictions. For light oil, capillary pressure still noticeably increased the level of supersaturation, and the critical gas saturation had a strong influence on the properties of produced fluids. For retrograde gas, the effect of capillary pressure was insignificant because of the low interfacial tension (IFT). Despite the choice of fluids, calculations indicate that the smallest pores are probably always occupied by hydrocarbon liquid during depressurization.

ZnO nanoplate-induced phase transformation synthesis of the composite ZnS/In(OH)3/In2S3 with enhanced visible-light photodegradation activity of pollutants

CrystEngComm ◽  
2014 ◽  
Vol 16 (48) ◽  
pp. 10997-11006 ◽  
Author(s):  
Yun Gu ◽  
Zhaodi Xu ◽  
Lan Guo ◽  
Yiqun Wan
Keyword(s):  
Phase Transformation ◽  
Band Structure ◽  
Visible Light ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Energy Band ◽  
Energy Band Structure

The as-synthesized composite ZnS/In(OH)3/In2S3 by phase transformation induced by ZnO nanoplates exhibits excellent photoactivity due to the suitable energy band structure and wider pore size distribution.

scholarly journals Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yusen Wei ◽  
Youming Xiong ◽  
Zhiqiang Liu ◽  
Jingsheng Lu
Keyword(s):  
Phase Transition ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Thermal Diffusion ◽  
Gas Hydrate ◽  
Reservoir Rock ◽  
Maximum Temperature ◽  
Endothermic Reaction ◽  
Surface Relaxivity

Methane hydrate is the vast potential resources of natural gas in the permafrost and marine areas. Due to the occurrence of phase transition, the gas hydrate is dissociated into gas and water and absorbs lots of heat. The incomprehensive knowledge of endothermic reaction in permafrost sediments still restricted the production efficiency of hydrate commercial development. This endothermic reaction leads to a complex thermal diffusion in permafrost, which directly influences the phase transition in turn. In this research, the heat during the exploitation is transferred in two forms (specific heat and latent heat). Besides, the melting point is not constant but depends on the pore size of the reservoir rock. According to these features, a thermal diffusion model with phase transition is established. To calculate the governing equation, the pore size distribution is obtained by using the nuclear magnetic resonance (NMR) method. The heating tests are conducted and simulated to calibrate the coefficient (i.e., transverse surface relaxivity) of NMR. Then, the temperature field evolution of the hydrate reservoir during the exploitation is simulated by using the calibrated values. The results show that the temperature curves have a typical plateau related to the pore size distribution, which is effective to obtain the surface relaxivity. The heat transfer is remarkably limited by the endothermic effect of the phase transition. The hydrate recovery efficiency may depend largely on the heating capacity of the engineering operation and the rate of gas production. Compared to the conventional petroleum industry, it is significant to control the maximum temperature and temperature distribution in engineering operations during hydrate development. This research on the temperature behavior during onshore permafrost hydrate production could provide the theoretical support to control heat behavior of offshore hydrate production.

Effective Dewetting in a Microporous Particle

2005 ◽  
Vol 127 (6) ◽  
pp. 1128-1131 ◽  
Author(s):  
Yu Qiao ◽  
Xinguo Kong
Keyword(s):  
Phase Transformation ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Volume Fraction ◽  
Dewetting Process ◽  
Nonwetting Liquid ◽  
Effective Phase ◽  
Kinetics Of ◽  
Nucleation Growth

In this paper, the kinetics of the outflow in a microporous particle infiltrated by a nonwetting liquid is analyzed in context of effective phase transformation. The “dewetting” process is considered as the nucleation, growth, and coalescence of empty pore clusters (EPCs) that starts from the interior and eventually involves the whole particle. Initially, the EPC nucleation is dominant while the influence of EPC coalescence becomes increasingly important as the EPC volume fraction increases. The dependence of the dewetting time on the pore size distribution is discussed in detail.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

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