نتایج جستجو برای: mcm 41
تعداد نتایج: 93407 فیلتر نتایج به سال:
Present study demonstrated the preparation of MCM-41 as a support for the immobilization of Candida rugosa lipase by the physical adsorption technique. The lipase immobilized MCM-41 has been characterized by scanning electron microscopic and FTIR techniques. At pH 6, maximum lipase immobilization (250 mg/g) on MCM support has been observed and the immobilized lipase was employed as biocatalyst ...
The production of conjugated C4–C5 dienes from biomass can enable the sustainable synthesis many important polymers and liquid fuels. Here, we report first example bimetallic (Nb, Al)-atomically doped mesoporous silica, denoted as AlNb-MCM-41, which affords quantitative conversion 2-methyltetrahydrofuran (2-MTHF) to pentadienes with a high selectivity 91 %. incorporation AlIII NbV sites into fr...
The observation of molecular clusters has been of interest for some time. Molecular clusters can show quite different dynamic and static phase behaviour from bulk systems, and, because of their limited size, are accessible to computational molecular dynamics techniques.1-3 Experimentally, molecular clusters are made using several methods, including supersonic jets, vapours, confinement of phase...
سنتز جاذب mcm-41 به روش هیدروترمال در حضور اتانول بهعنوان حلال و ماده فعال سطحی کمکی و در محیط قلیایی انجام پذیرفت. جاذب معدنی zncl2-mcm-41 به روش پیوند کووالانسی با توزیع مواد در حلال تولوئن و از اندرکنش بین ذرههای zncl2 با گروههای سیلانول روی دیوارۀحفرههای mcm-41 تهیه شد. تعیین مشخصات این جاذب با استفاده از آزمایشهای جذب نیتروژن، xrd، طیف سنجی ftir و sem انجام شد. سطح فعال mcm-41بر اس...
the mesoporous molecular sieve mcm-41 was covalently grafted with 3-chloropropyl trimethoxylsilane and then was reacted with [cr(salpr)(h2o)]cl, (salpr = n,n'-bis(3-salicylidenaminopropyl)amine) to afford mcm-41 containing cr(salpr) moiety, cr(salpr)mcm-41. powder x-ray diffraction and nitrogen adsorption-desorption analyses revealed that not only the textural characteristics of the support wer...
ti-mcm-41 was synthesized at ph 3, 7 and 11. the titanium content was determined by aas and found to be 4%, 3.2% and 4.5%, respectively. in order to increase the titanium content in ti-mcm-41, ti(iv) ions were grafted onto ti-mcm-41 using ticl4 in toluene and ti(obu)4 in ethanol. the incorporation of ti was determined to be 28% and 30%, respectively. the oxidation of olefins such as cyclopenten...
the direct and indirect methods in solvent media and grinding method in a solvent-free media were used to prepare the mcm-41/zno and mcm-48/zno photocatalysts. the x-ray diffraction (xrd) patterns showed that zinc oxide nanoparticles were put into mcm-41 and mcm-48 substrates and there were zno crystallites as secondary phase in the extra framework of mesoporous materials. the decrease of surfa...
در این کار پژوهشی مزوپور mcm-41 به عنوان بستر جهت تهیه کاتالیزورهای ناهمگن سنتز شد. در بخش اول، جهت بارگذاری منگنز بر روی سطح mcm-41 ، محلول پتاسیم پرمنگنات در استونیتریل به mcm-41 افزوده شد. در مرحله بعد با استفاده از روش لیگند انعطاف پذیر، کمپلکس منگنز با لیگند شیف- باز سه دندانه ای n-2- هیدروکسی فنیل سالیسیلیدن ایمین در منافذ mcm-41 وارد و بوسیله طیف بینی ft-ir و آنالیز پراش پرتو ایکس ، xrd ...
The discovery of mesoporous molecular sieves, MCM-41, which possesses a regular hexagonalarray of uniform pore openings, aroused a worldwide resurgence in this field. This is not onlybecause it has brought about a series of novel mesoporous materials with various compositionswhich may find applications in catalysis, adsorption, and guest-host chemistry, but also it hasopened a new avenue for cr...
The mesoporous molecular sieve MCM-41 was covalently grafted with 3-chloropropyl trimethoxylsilane and then was reacted with [Cr(salpr)(H2O)]Cl, (salpr = N,N'-bis(3-salicylidenaminopropyl)amine) to afford MCM-41 containing Cr(salpr) moiety, Cr(salpr)MCM-41. Powder X-ray diffraction and nitrogen adsorption-desorption analyses revealed that not only the textural characteristics of the support wer...
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