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Home > Transient Non-Thermal Mobility in Surface Subsurface Hetrogeneous Catalytic Reaction: Computer Simulation

Transient Non-Thermal Mobility in Surface Subsurface Hetrogeneous Catalytic Reaction: Computer Simulation

Thesis Info

Access Option

External Link

Author

Qaisrani, Abaid Ullah

Program

PhD

Institute

Gomal University

City

Dera Ismail Khan

Province

KPK

Country

Pakistan

Thesis Completing Year

2007

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/282

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727629783

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To study the effect of transient non-thermal mobility in surface-subsurface heterogeneous catalytic reaction, simulation work has been done for CO-O2 and CO- NO catalytic reaction on different surfaces. One class of transient non-thermal mobility of species includes Ely-Rideal (ER) mechanism. The first simple lattice gas model was introduced by Ziff, Gulari and Barshad, as a computer simulation model and is known as the ZGB model, which was used to study CO- O2 reaction system. It has been found through simulation that ER mechanism generates features in the ZGB model that brings it closer to the real system. The Consideration of ER mechanism annihilates second order phase transition of the ZGB model and the reaction rate begins to increase as soon as feed concentration CO departs from zero, which is consistent with the experimental results. The other class of transient non-thermal mobility is precursor mechanism. This mechanism adds some additional features in the phase diagram of a particular catalytic reaction, which could not be observed by considering the Langmuir-Hinshelwood mechanism. In the precursor mechanism, three different ranges of the surface environment have been investigated. Each environment consists of specific pattern for set of sites around the striking site. It is observed that the reactive window depends on the mobility of the precursors. It is also observed that when the probability of the precursor is increased, the production rates increases. Furthermore, the simulation is also performed to investigate the effect of diffusion of CO on the ZGB model. It has been found that the effect of diffusion of CO on the ZGB model is to increase the mobility of CO on the surface and hence the reaction rate increases with the result that the transition point y2 shifts towards higher concentration of CO. However, the effect of diffusion of CO has no effect on the second order phase transition point y1. The effect of diffusion of CO and N (atom) for CO-NO catalytic reaction has also been studied on BCC lattice. The effect of diffusion of CO and N on the production rates is found in the high concentration of CO. This mechanism is found responsible for slight increase in the window width where the concentration of CO is high. Through these models some experimental results have been reproduced of the real system.
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مولاناابوبکر محمد شیث جو نپوری

مولانا ابوبکر محمد شیثؔ جونپوری
افسوس ہے کہ شیث جونپوری نے دو ڈھائی برس کی سخت علالت کے بعد اپنے وطن جونپور میں ۲۳؍ شعبان ۱۳۵۹؁ھ مطابق ۲۶؍ ستمبر ۱۹۴۰؁ء کی رات کو ۳ بجے اس جہانِ فانی کو الوداع کہا، اناﷲ وانا الیہ راجعون۔
مر حوم جونپورکے ایک مشہور علمی خاندان کے فرد تھے،اُن کے دادا مولانا سخاوت علی صاحب مولانا شاہ عبد الحئی صاحب دہلوی اور مولانا اسماعیل شہید کے فیض یافتہ اور پورب میں توحید و سنت کے سب سے بڑے داعی، اور اس دور میں اسلامی علوم وفنون کے بہت بڑے مدرس تھے، جونپور میں بیٹھ کر تنِ تنہا سینکڑوں علمائے دین پیدا کئے اور پورب کے خطّہ میں اُن کو جگہ جگہ پھیلا کر اس نازک مو قع پر اسلام کی مو رچہ بندی کی، وہ ہجرت کرکے بعد کو مدینہ منورہ چلے گئے تھے اور وہیں وفات پائی، راقم کو بھی یہ فخر حاصل ہے کہ اس کے دادا کے حقیقی بھائی انھیں کی مجلسِ درس سے مستفیض تھے۔
مو لانا کا پورا خاندان اس وقت سے اب تک علمائے دین کا خانوادہ ہے، جس کی سعی و کوشش نے پورب کی سرزمین کو بڑا فیض پہنچایا، مولانا مرحوم نے نیچے کی تعلیم گھر میں پاکر مولانا عبداﷲ صاحب غازی پوری سے مدرسۂ احمدیہ آراہ جاکر علوم کی تحصیل کی، اور واپس آکر اپنے خاندانی مدرسہ کے اہتمام وانتظام کا اور ساتھ ہی ملک کے مختلف گوشوں میں جاکر ہدایت و ارشاد کا کام انجام دینا شروع کیا۔
موصوف سے میری ملاقات ۱۹۲۰؁ء میں تحریک خلافت کے سلسلہ میں ہوئی ،یہ ملاقات دوستی، اور دوستی سے اتحاد کی اس منزل تک پہنچ گئی جس کے بعد خیال کی دوئی کا کوئی مرتبہ نہیں رہتا، ایک دفعہ میں نے کہا اور اُنھوں نے مانا تھا کہ ایک مذہب ہے جس کے دو...

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Performance Evaluation of Membrane Contactors for Concentration of Fruit Juices Through Osmotic Distillation

Osmotic distillation (OD) of apple and pomegranate juices was performed with membrane contactors. In the first part of the study, apple juice was concentrated through OD process using hollow fiber module. For feed-in-fiber flow set-up, final juice concentration of 47oBrix with a water permeate flux of 0.047 kg.m-2.hr-1, while for the feed-in-shell flow arrangement, final juice concentration of 52oBrix with a water permeate flux of 0.089 kg.m-2.hr-1 was achieved in a total time of 320 minutes. Fouling effect on the performance of polypropylene hollow fiber module was evaluated for pomegranate juice concentration through OD. A final concentration of 52.0°Brix with a water permeate flux of 0.186 kg.m-2.hr-1 was achieved in a total time of 310 minutes. Morphological analysis of the membrane surface and cross sections revealed that the significant pore blockage occurred due to fouling after persistent operation. However, it was found that rigorous membrane cleaning protocol, promoted higher water permeate flux. Pomegranate juice was also subjected to OD process using PVDF and PTFE membranes in flat sheet module. Wetting behavior of the membranes was evaluated through various analytical techniques. It was found that PVDF membrane had least resistance to wetting which resulted in a lower water permeate flux of 0.208 kg.m-2.hr-1 in a total time of 24 hours. On the other hand, a nice resistance to wetting was shown by PTFE membrane. A water permeate flux of 0.935 kg.m-2.hr-1 was achieved in an operational time of 24 hours. Therefore, PTFE membrane showed an ample potential for semiindustrial/industrial scale applications.