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Home > Catalytic Studies of Butadiene/Ethylene Polymerization

Catalytic Studies of Butadiene/Ethylene Polymerization

Thesis Info

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Author

Naheed, Rafia

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2012

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/1760

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725666211

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In present study, the polymerization of butadiene and ethylene were carried out using heterogeneous monometallic, bi-and tri-metallic catalysts. Five types of catalysts, nickel, cobalt monometallic, Ni-Co bi-metallic, and Ni-Co-Pd, Ni-Co-Pt tri-metallic were synthesized by using sol-gel, impregnation and hydrometallurgical methods. The synthesized nano composites were subjected to calcinations at 200, 400, 600 and 900 oC, to study their effects on catalyst morphology, activity and product selectivity. These were characterized by X-ray diffraction (XRD), helium adsorption Brunaur, Emmett and Teller (BET), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometer (EDX), transmission electron microscopy (TEM), FT-IR Spectroscopy, temperature programmed reduction (TPR), temperature programmed oxidation (TPO) and X-ray Photoelectron spectroscopic (XPS) studies. The synthesized catalysts were tested for the polymerization of butadiene and ethylene in ethanol, n-hexane and toluene solvents at various temperature and pressure conditions in Parr reactor. The products obtained were characterized by Fourier transform infrared spectroscopy FT-IR, 1H and 13 C Nuclear magnetic resonance spectroscopy (NMR), Gel permeation chromatography (GPC), Thermogravimetric analysis (TGA), Static laser light scattering (SLLS) and Mass spectrometric analysis (MS). The results showed that in ethanol solvent at 130 °C and 1.0 barr pressure, the product obtained consists of aliphatic and aromatic carbonyl compounds and polybutadiene terminated by -OH group. The selectivity of product was obtained in n-hexane and toluene solvent. In order to synthesize hydroxyl group terminated polybutadiene HTPB, the termination of polybutadiene was carried out by acidic solution of ethanol or hydrogen peroxide, whereas the termination of polyethylene was carried out by the acidic solution of ethanol. The significant product was achieved with the catalyst prepared by hydrometallurgical method as compared to other techniques. The best results were achieved with the Ni-Co- Pt catalyst calcined at 900 oC with molecular weight average of 12414 and a polydispersity Mw/Mn value of 1.404 under controlled conditions of temperature 130 oC and pressure 1.0 barr. The microstructure distribution of polybutadiene was studied by carrying out catalytic activity test at different temperature and pressure conditions. 100% stereoregular product of cis-1,4 polybutadiene have been achieved at low temperature 30 oC and pressure 0.5 barr with the catalyst Ni-Co calcined at 900 oC.
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متنی تنقید اور اس کے مدارج

موضوع7:متنی تنقید اور اس کے مدارج
متنی تنقید :
انسائیکلو پیڈیا ’ امریکانا ‘ نے متنی تنقید کی تعریف کرتے ہوئے لکھا ہے :
’’ متن کے اصل الفاظ کے تعین، اسے مکمل کرنے اور واقفیت واصلیت تلاش کرنے کی غرض سے پرانی تحریروں کے سائینٹفک مطالعے کو متنی تنقید کہتے ہیں۔ ‘‘
متنی تنقید کا اصل مقصد حتیٰ الامکان متن کو اصل روپ میں دوبارہ حاصل کرنا ہوتا ہے۔ اصل روپ سے مراد وہ شکل وصورت ہے جو متن کا مصنف اپنی تحریر کو دینا چاہتا تھا۔ یعنی اگر متنی نقاد کو مصنف کے ہاتھ کا لکھا ہوا نسخہ ملا ہے تو اسے متنی نقاد من وعن ہی شائع نہیں کرسکتا کیونکہ ممکن ہے مصنف سے کچھ الفاظ چھوٹ گئے ہوں یا کچھ الفاظ دوبارہ لکھ دئیے گئے ہوں یا اس قسم کی کوئی اور غلطی ہوئی ہو۔ ایسی صورت میں متنی نقاد کا فرض ہے کہ متن کو ان غلطیوں سے پاک کرے۔ متن کے لیے ضروری ہے کہ بامعنی ہو، اگر سینکڑوں برس کے عرصے میں نقل در نقل کی وجہ سے متن مسخ ہوگیا ہے تو اس کے اصل معنی کا تعین کیا جاسکے۔
متنی تنقید/تنقیدِ متن کے مدارج :
۱۔ تیاری ۲۔ مواد کی فراہمی
۳۔ متن کی تصحیح ۴۔ قیاسی تصحیح
۵۔ اعلیٰ تنقید
۱۔ تیاری :
الف۔مختلف عہد کے نسخے پڑھنا :
متنی نقاد کا فرض ہے کہ مختلف عہد کی تحریروں پر عبور حاصل کرنے کے لیے ان عہدوں کے نسخے پڑھے تاکہ تحریر کی شناخت کے ساتھ ساتھ اس عہد کے الفاظ وتحریر پر اسے عبور حاصل ہوسکے۔ متنی نقاد کو اس عہد سے قبل کے کچھ نسخے بھی پڑھنے چاہئیں۔ اس انتخاب کے باقاعدہ اصول تو نہیں ہیں لیکن اس عہد میں جولوگ ادب پر چھائے ہوں ان میں سے نمایاں لوگوں کو منتخب کرلیا جائے۔

Efforts to Improve the Creative Economy During the Covid-19 Pandemic in Asean Countries

Increasing the creative economy during the pandemic is very urgent, as an effort to stabilize the economy in ASEAN. The character of the creative economy is characterized by economic activities that are based on the exploration and exploitation of creative ideas that have high selling value. All tourism ministers from ASEAN countries to strengthen tourism cooperation, one of the economic sectors hardest hit in the pandemic. Intelligent marketing is needed in order to know the strengths of our competitors and market tastes, because in the era of globalization, war is actually a war in the economic field and the creative economy is the main weapon. Strong cooperation in efforts to jointly handle the impact of COVID-19 in the tourism sector in the ASEAN region. All ASEAN members to jointly enhance cooperation not only in dealing with pandemic problems but also in terms of developing the creative economy.

Identification of Prospective Inhibitor for Tryptophan Synthase to Combat Tuberculosis

The current study was aimed to identify new inhibitors against tryptophan synthase from Mycobacterium tuberculosis for anti-tuberculosis drug discovery. The α-subunit of tryptophan synthase being unique and unexplored protein target was selected for discovery of new inhibitors that can serve as leads for anti-TB drugs discovery with novel mode of action. Here a combination of computational and experimental approaches was utilized. Both the structure based (SB) and ligand based (LB) virtual screening approaches were employed for prediction and identification of new hits as inhibitors against α-subunit of tryptophan synthase from M. tuberculosis. The structure based virtual screening (SBVS) of eMolecules database was done against homology model for protein i.e., α-subunit of tryptophan synthase. Seven new inhibitors were identified on the basis of their binding score, binding interactions and physiochemical properties. Similarly, ligand based virtual screening (LBVS) was used for screening of “clean drug like” subset of ZINC database against pharmacophore model. This pharmacophore model was generated using the structures of already reported inhibitors of the α-subunit of TrpS from literature and hits were identified in terms of rmsd (<1). Later the molecular docking studies of hits into the active pocket resulted in identification of five new inhibitors against α-subunit of TrpS. The anti-tuberculosis activity of proposed inhibitors identified through SBVS and LBVS was performed using agar dilution method and LJ media based method that resulted in identification of a new benzamide inhibitor and ZINC09150898. The benzamide inhibitor showed 100% growth inhibition of H37Rv strain of M. tuberculosis at 25 μg/mL and considerable anti-mycobacterial effect up to 6 μg/mL in whole cell based activity. The second new inhibitor i.e., ZINC09150898 showed antibacterial activity against H37Rv strain of M. tuberculosis at the concentration of 50 µg/mL (100% inhibition) and partial inhibition up to 12 µg/mL. The binding stability of both benzamide inhibitor and ZINC09150898 inside the binding pocket was further investigated through MD simulation studies involving RMSD, RMSF and secondary structure analysis that showed no major structural fluctuations in protein structure during the explored time scale. The current study can be further extended for enzyme based assay evaluation and could be considered as candidate for drug discovery against tuberculosis. In our attempt to find out new lead candidates for anti-tuberculosis drug discovery we performed in silico comparison of putative drug binding pockets of twelve essential metabolic enzymes from M. tuberculosis and other bacterial pathogens belonging to the ESKAPE group. The aim of this comparative analysis was to provide guidelines for the likelihood of transferability of the inhibitors from one species to another. In this comparison pathways other than tryptophan biosynthesis were investigated and the selection of targets was based on availability of the 3D-structure. Drug binding pockets of these essential enzymes from selected metabolic pathways that were conserved across ESKAPE pathogens, M. tuberculosis, M. smegmatis and E. coli were compared using their reported 3D structures and amino acid sequence alignment. This comparative analysis showed that drug binding pockets of these enzyme are mostly identical with good sequence identity (70-100 %) across different species used in this study suggesting that inhibitor designed for enzyme target of one species may have chances to inhibit same enzyme target in other species as well. This study suggested that antibiotics targeting enzyme of one pathogen might have similar inhibitory potential against other bacterial species as well if their binding pockets are conserved and can effectively help in design of new antibiotics against M. tuberculosis and ESKAPE pathogens as well as.