دانلود رایگان مقاله لاتین نقش اکسید در کربندار کردن اتیلن گلیکول از سایت الزویر
عنوان فارسی مقاله:
نقش اکسید در کربندار کردن اتیلن گلیکول به کربنات اتیلن با اوره: یک پیشرو برای کاتالیزور همگن
عنوان انگلیسی مقاله:
The role of zinc oxide in carbonylation of ethylene glycol to ethylene carbonate with urea: A precursor for homogeneous catalyst
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Ethylene carbonate (EC) is a commercially important starting chemical or intermediate for selective alkoxylation, carbamate formation, the processing agents of polymers etc. [1,2]. Most importantly EC is a critical reagent for dimethyl carbonate (DMC) production by transesterification with methanol. Equimolar amount of ethylene glycol (EG) and DMC is formed in this reaction [3]. While the commercialized path of EC is produced by the coupling of carbon dioxide and ethylene oxide cycloaddition reaction [4], therefore, 1 mol of ethylene oxide needs to be consumed to produce 1 mol DMC and EG. However, ethylene oxide is more expensive than EG due to the different demands on EG and ethylene oxide in some places. Therefore, a new approach to produce EC has to be developed from an economic aspect. EG can react with urea generating NH3 and EC which can be transesterificated to DMC with a side product of EG in the presence of methanol. The side product of EG here can be further recycled as a reactant in the production of EC. On the other hand, NH3, the side product of EC production, can be recycled as a reactant for urea production with CO2. Overall, as the reaction (EG + urea = EC + NH3) start, only methanol and CO2 need to be fed to produce DMC [5]. Various metal oxides have been prepared and utilized as catalysts for the carbonylation of EG to EC with urea, such as CaO, La2O3, MgO, ZnO, Al2O3, ZnO-Fe2O3, and ZnO-Cr2O3 [5–9]. Among them, Zn-contained catalysts show the best performance with high activity and selectivity. ZnO has been considered to be one of the candidates for this reaction. The reactions in the presence of ZnO are often regarded as heterogeneously catalytic processes [5–9]. The amount and balance of acidic and basic sites have been taken into account as the key factors for the good catalytic performance of ZnO [9,10]. However, we observed that ZnO could be dissolved completely into the reactants as the temperature was increased, suggesting that ZnO possibly experienced a phase transition in the reaction. As a result, the reaction was in fact carried out in a homogeneous phase. Generally, ZnO is insoluble in EG. It has been reported that ZnO was dissolved during the reaction of urea and methanol to DMC [11,12]. Differently [12], precipitate was observed after the reaction proceeded for a certain period in the current case. Hereby, we attempted to clarify the catalytic role of ZnO during synthesis of EC from urea and EG. In order to elucidate the mechanism, the precipitate was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), inductively coupled plasma (ICP), and CNH elemental analysis.
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کلمات کلیدی:
The role of zinc oxide in carbonylation of ethylene glycol to ... - Trove trove.nla.gov.au/work/217040809? Jan 10, 2017 - 2017-01-10, English, Article, Journal or magazine article edition: The role of zinc oxide in carbonylation of ethylene glycol to ethylene ... Synthesis of ethylene carbonate from urea and ethylene glycol over ... onlinelibrary.wiley.com/doi/10.1002/jctb.1872/abstract by X Zhao - 2008 - Cited by 12 - Related articles Feb 8, 2008 - Abstract. BACKGROUND: Ethylene carbonate (EC) was synthesised via urea and ethylene glycol (EG) over zinc/iron oxide catalyst. Synthesis of ethylene carbonate from cyclocondensation of ethylene ... www.eurjchem.com › Home › Vol 3, No 2 (2012) by S Bhadauria - 2012 - Cited by 12 - Related articles ZnO·Cr2O3 catalyst has been synthesized by low temperature, pH controlled ... The role of zinc oxide in carbonylation of ethylene glycol to ethylene carbonate ... [PDF]Transesterification of urea and ethylene glycol to ... - The Vespiary https://www.thevespiary.org/.../1354-Transesterification-of-urea-and-ethylene-glycol-... by BM Bhanage - 2003 - Cited by 106 - Related articles The first step involves reaction of urea with ethylene glycol (EG) to form ethylene carbonate (EC) and the ... carbonylation. ... The importance of dimethylcarbonate in many application ... simple and inexpensive catalyst ZnO is highly active and. Introduction to Industrial Chemistry - Page 238 - Google Books Result https://books.google.com/books?isbn=047182657X Howard L. White - 1986 - Science ... acid from p-xylene, 103- 104 ethylene glycol from syngas: carbonylation. ... 98-99 copper-zinc, 92 iron (II) oxide, 78 manganese acetate, 69 manganese ... The role of zinc oxide in carbonylation of ethylene glycol to ethylene ... en.tjufe.findplus.cn/?h=articles&db=edselp&an... Translate this page Short communication: The role of zinc oxide in carbonylation of ethylene glycol to ethylene carbonate with urea: A precursor for homogeneous catalyst.
