Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 6

年份

2022 1

2021 1

2014 2

2012 1

2011 1

关键词

分子筛膜 1

工业应用 1

有机溶剂脱水 1

渗透汽化 1

检索范围：

排序：展示方式：

The dehydration behavior and non-isothermal dehydration kinetics of donepezil hydrochloride monohydrate

Tiantian LIU, Yuanyuan RAN, Bochao WANG, Weibing DONG, Songgu WU, Junbo GONG

《化学科学与工程前沿（英文）》 2014年第8卷第1期页码 55-63 doi: 10.1007/s11705-013-1352-3

摘要： Powders of donepezil hydrochloride monohydrate (Form I) underwent isomorphic dehydration, losing 3% w/w water between 90% and 10% relative humidity (RH) without changing its powder X-ray pattern. Below 10% RH, additional dehydration occurred in conjunction with a reversible phase transition between the monohydrate state and a dehydrated state, with a 4.0% w/w loss to 0% RH. A combination of methods was used to understand the structural changes occurring during the desolvation process, including dynamic vapor sorption measurements, thermal analysis and powder X-ray diffraction. Form I showed the characteristics of the channel hydrate, whose non-isothermal dehydration behavior proceeds in two steps: (1) the loss of non-crystalline water adsorbed on the surface, and (2) the loss of one crystalline water in the channel. Dehydrated Form I is structurally similar to the monohydrate Form I. According to the heat of fusion and the crystal density criteria, the two crystal forms belonged to the univariant system, and the anhydrate (Form III) is stable. The dehydration kinetics was achieved from the TG-DTG curves by both the Achar method and the Coats-Redfern method with 15 frequently cited basic kinetic models. The dynamic dehydration processes for steps 1 and 2 were best expressed by the Zhuralev-Lesokin-Tempelman equation, suggesting a three-dimensional diffusion-controlled mechanism.

关键词： dehydration thermal analysis transformation dehydration kinetics

HTML PDF 收藏

Investigations on dehydration processes of trisodium citrate hydrates

Junyan GAO, Yanlei WANG, Hongxun HAO

《化学科学与工程前沿（英文）》 2012年第6卷第3期页码 276-281 doi: 10.1007/s11705-012-1206-4

摘要： The dehydration processes of trisodium citrate (Na C H O ) hydrates were investigated using thermogravimetry (TG), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). It was found that the temperature of dehydration of trisodium citrate dihydrate was at 430.99 K. For trisodium citrate pentahydrate, there is a two-step dehydration process and the endothermal peaks appear at 337.23 K and 433.83 K, respectively. During the first step of dehydration process, the structure of trisodium citrate pentahydrate changed into the structure of trisodium citrate dihydrate. In addition, the kinetics of dehydration for trisoidum citrate hydrates was also investigated using TG data. According to the activation energies of dehydration calculated by Ozawa equation, it was found that the dehydration mechanisms of the two hydrates were different.

关键词： trisodium citrate dehydration TG/DSC PXRD

HTML PDF 收藏

Effects of the SAPO-11 synthetic process on dehydration of ethanol to ethylene

Lina WU, Xiaoxing SHI, Qun CUI, Haiyan WANG, He HUANG

《化学科学与工程前沿（英文）》 2011年第5卷第1期页码 60-66 doi: 10.1007/s11705-010-0540-7

摘要： The effects of the synthetic condition of SAPO-11 molecular sieves on ethanol dehydration to ethylene were studied. Product-compositions, ethanol conversion, and selectivity to ethylene of synthesized and commercial SAPO-11 molecular sieves were compared. Results are as follows: the optimal synthetic conditions for SAPO-11 molecular sieves are adding pseudoboehmite before orthophoshporic, using di-n- propylamine as the template, having a mass fraction of 40% colloidal silica as the silica source and the starting gel obtained, and running at 200°C for 48 h. From the patterns of NH -TPD, the amount of acid synthesized by SAPO-11 molecular sieves is less than that by commercial SAPO-11 molecular sieves, and has a stronger weak acid. Also, ethanol conversion and selectivity to ethylene reached 99% at 280°C on synthesized SAPO-11, lower by 20°C compared to commercial SAPO-11. For two SAPO-11 molecular sieves, the by-products in the gas phase are mainly ethane, propane, propene, isobutane, n-butane, propadiene, butylene and some higher hydrocarbons. The by-products in the liquid phase are ethyl ether and acetaldehyde.

关键词： SAPO-11 molecular sieves synthesis ethanol ethylene dehydration

HTML PDF 收藏

Dehydration of natural gas and biogas streams using solid desiccants: a review

Soheil Bahraminia, Mansoor Anbia, Esmat Koohsaryan

《化学科学与工程前沿（英文）》 2021年第15卷第5期页码 1050-1074 doi: 10.1007/s11705-020-2025-7

摘要： Natural gas and biogas are two mixtures that consist of methane as their main component. These two gas mixtures are usually saturated with water vapor, which cause many problems, such as damaging the gas processing equipment by increasing the gas’s corrosion potential or clogging the pipelines due to gas hydrate formation. Thus, removing water vapor from these gas streams is mandatory. In this review paper, the main dehydration methods have been overviewed, and scrutiny of the adsorption dehydration has been carried out. Furthermore, the most important solid desiccants and their improvements have been reviewed.

关键词： natural gas biogas dehydration adsorption solid desiccant

HTML PDF 收藏

渗透汽化脱水分子筛膜的制备与应用研究

顾学红,徐南平

《中国工程科学》 2014年第16卷第12期页码 52-58

摘要：

开发了擦涂-浸渍涂晶法和亚微米晶种诱导制备NaA分子筛膜技术，有效地提高了膜的成品率、缩短了合成时间，获得了适合规模化生产的制膜工艺。通过分子模拟的方法，对有机溶剂和水在分子筛膜中的传质机理进行了探讨。对NaA分子筛膜在体系中的水热、酸碱和盐稳定性进行了系统地研究，提出了相应的预处理工艺，并设计建造出渗透汽化工业应用装置，实现了长时间稳定运行。

关键词：渗透汽化分子筛膜有机溶剂脱水工业应用

HTML PDF 收藏

Micro-sized hydrothermal carbon supporting metal oxide nanoparticles as efficient catalyst for mono-dehydration

Cheng PAN, Chao FAN, Wanqin WANG, Teng LONG, Benhua HUANG, Donghua ZHANG, Peigen SU, Aqun ZHENG, Yang SUN

《能源前沿（英文）》 2022年第16卷第5期页码 822-839 doi: 10.1007/s11708-020-0677-0

摘要： Most known catalytic dehydration of sugar alcohols such as D-sorbitol and D-mannitol can only produce di-dehydrated forms as major product, but mono-dehydrated products are also useful chemicals. Moreover, both di- and mono-dehydration demand a high temperature (150°C or higher), which deserves further attentions. To improve the mono-dehydration efficiency, a series of metal-containing hydrothermal carbonaceous materials (HTC) are prepared as catalyst in this work. Characterization reveals that the composition of preparative solution has a key influence on the morphology of HTC. In transformation of D-sorbitol, all HTC catalysts show low conversions in water regardless of temperature, but much better outputs are obtained in ethanol, especially at a higher temperature. When D-mannitol is selected as substrate, moderate to high conversions are obtained in both water and ethanol. On the other hand, high mono-dehydration selectivity is obtained for both sugar alcohols by using all catalysts. The origin of mono-dehydration selectivity and role of carbon component in catalysis are discussed in association with calculations. This study provides an efficient, mild, eco-friendly, and cost-effective system for mono-dehydration of sugar alcohols, which means a lot to development in new detergents or other fine chemicals.

关键词： hydrothermal carbon morphology catalyst mono-dehydration sugar alcohol