نتایج جستجو برای: bronsted acid

تعداد نتایج: 747476  

2015
Meilin Tao Lifang Xue Zhong Sun Shengtian Wang Xiaohong Wang Junyou Shi

In order to investigate the influences of Lewis metals on acidic properties and catalytic activities, a series of Keggin heteropolyacid (HPA) catalysts, HnPW11MO39 (M = Ti(IV), Cu(II), Al(III), Sn(IV), Fe(III), Cr(III), Zr(IV) and Zn(II); for Ti and Zr, the number of oxygen is 40), were prepared and applied in the esterification and transesterification reactions. Only those cations with moderat...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد علوم دارویی - دانشکده داروسازی 1392

از آنجا که دانه ی گیاه خرفه منبع غنی ای از اسید های چرب ضروری میباشد لذا نیازمند روشی کارامد جهت استخراج بهینه این اسیدهای چرب میباشیم.با توجه به مزایای روش استخراج با سیال فوق بحرانی شامل سرعت استخراج,گزینش پذیری و کنترل حلالیت,اثر پیش تغلیظ کنندگی, کمی بودن استخراج,تمیزی و ایمنی, دمای پایین ,سادگی ,صرفه جویی در هزینه و قابلیت ادغام با تکنیک های دیگراین روش جدید استخراج برای استخراج اسیدهای چر...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده شیمی 1393

چکیده در این پایان نامه، در ابتدا از واکنش بین پالادیم استات و آلیزارین زرد gg کمپلکس دو هسته ای ارتوپالادیت [pd{? 2(c,n) -{5-(3-nitrophenylazo) salicylic acid}}(µ-oac)]2 (1) ستنز شد. از واکنش این کمپلکس دو هسته ای ارتوپالادیت (1) با لیگاند های تک دندانه تری فنیل فسفین (pph3)، 6،4،2-تری متیل-پیریدین(me3py) کمپلکس های تک هسته ای (2)، (3) سنتز شدند. همچنین از واکنش بین پالادیم استات و آلیزارین ز...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شاهد - دانشکده علوم پایه 1388

introduction acetic acid bacteria are large group of obligate aerobic gram negative bacteria with the ability to oxidize ethanol to acetic acid (1). they are widely distributed in natural habitats and classified in family acetobacteraceae. members of this family are useful in industrial production of vinegar(2). acetic acid bacteria (aab) can use substrates as glucose, ethanol, lactate or glyc...

2006
J. RAVICHANDRAN

-The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of overall acidity and density of acidic sites. Infrared (IR) spectral and differential ...

2004
Steen Steenken

Diphenyl-, aryl-a-siloxyand %-furany1 carbenes can be protonated by even weak proton donors such as alcohols (by a bimolecular or by a pre-association mechanism involving more than one alcohol molecule) to yield the corresponding carbenium ions, whose spectra and electrophilic patterns of behavior are described. INTRODUCTION Proton transfer reactions to and from heteroatoms (= "normal" Bronsted...

Journal: :Industrial & Engineering Chemistry Research 2021

Efficient and one-pot conversion of biomass-derived carbohydrate into highly value-added 5-hydroxymethylfurfural (HMF) is a crucial reaction step for the valorization biomass resources toward bio-based chemicals fuels. In this work, series Sn/SAPO-34 catalysts were prepared through impregnation evaluated in glucose to HMF. The physicochemical properties systematically characterized by SEM, XRD,...

Journal: : 2023

Link for citation: Nazarova G.Y., Ivashkina E.N., Maltsev V.V. Calculation of thermodynamic and kinetic parameters catalytic cracking reactions on Lewis Brønsted acid sites. Bulletin the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 214-225. In Rus. The relevance research is caused by emerging necessity developing a mathematical model to optimize heterogeneous...

2006
G. W. KUNZE

T H E NATURE of pyridine adsorption by acidand base-saturated montmorillonite from Otay, California (A.P.I, no. H-24) was studied by infrared adsorption. The spectrum for chemisorbed pyridine was found to be distinctively different from physically adsorbed pyridine; the latter gave a spectrum very similar to liquid pyridine. Upon exposure of the clay films to pyridine at low vapor pressures, on...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1392

a novel acrylic acid-functionalized fe3o4 magnetic nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperacid in chemical transformations. the structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (tem), thermogravimetric analysis (tga), and ft-ir...

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