Search or add a thesis

Advanced Search (Beta)
Home > Γ-Al2o3 Supported Bimetallic Catalysts: Synthesis and Applications for Hydrazine Decomposition

Γ-Al2o3 Supported Bimetallic Catalysts: Synthesis and Applications for Hydrazine Decomposition

Thesis Info

Access Option

External Link

Author

Firdous, Naveeda

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9060/1/Naveeda_Firdous_Chemistry_HSR_2018_QAU_02.03.2018.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727681301

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


The main objective of the present research work was to explore the potentially unique properties and possible synergistic effect in supported bimetallic catalysts which were synthesized in two stages by adopting simple route. γ-Al2O3 granules were selected as a support material and prepared by sol gel process followed by oil drop method for granulation purpose. Co was chosen as low cost, basic metal and four noble metals (M): Ir, Ru. Pt, and Pd were selected as promoters. Four series of γ-Al2O3 supported bimetallic catalysts, (CoMx/γ-Al2O3) were synthesized via wet impregnation by loading ~ 20 wt% of Co metal and 0-5 wt% of promoter metals onto γ-Al2O3 in each series. On the basis of mole fraction (x) of promoter metals, the catalyst series were named as CoIrx/γ-Al2O3, CoRux/γ-Al2O3, CoPtx/γ-Al2O3, and CoPdx/γ-Al2O3. The prepared catalysts were characterized by various techniques i.e., Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) along with EDX analysis, transmission electron microscopy (TEM), surface area analysis, and temperature programmed reduction/oxidation (TPR/TPO) processes. In order to explore the diverse role, the synthesized catalysts were applied for hydrogen generation from two model reactions i.e., catalytic decomposition of hydrazine in a self-designed reactor and electro-oxidation of hydrazine by cyclic voltammetry (CV) technique. The catalytic decomposition of hydrazine (0.5 M) was performed at 25 oC and volume of gaseous products (H2+N2) was measured by a gravimetric water displacement method. The catalytic efficiency was evaluated in terms of turn over frequency (TOF) and selectivity (X) towards hydrogen generation. The optimal composition from each series was selected on the basis of activity and selectivity. Hydrazine decomposition reaction was further tested at various temperatures and activation energy (Ea) values were calculated from the kinetic profiles using Arrhenius equation. In particular, the kinetic studies depicted an increase in rate of hydrogen generation with an increase in temperature up to 65 oC. The effect of support was also studied by loading the selected optimal composition on various supports including MgO, ZnO, SiO2, and zeolite; (γ-Al2O3 proved to be the best iv support candidate). For electrochemical studies, glassy carbon electrode was modified with each catalyst powder by drop-casting and used for investigating electro-oxidation of hydrazine analyte in 0.1 M phosphate buffer solution (pH 7.2). Cyclic voltammetry was performed to elucidate the redox behavior of synthesized electroactive materials. A linear current-voltage response was observed on the modified electrodes in each catalyst series. The stability and reproducibility of all the catalytic materials was substantiated by the catalytic activity as measured in many successive cycles. All bimetallic catalysts showed potentiality for hydrogen generation and electrochemical applications. The combination of high TOF and selectivity for hydrogen generation as well as prominent current response in CV studies rendered CoIr0.081/γ-Al2O3, CoRu0.11/γ-Al2O3, CoPt0.034/γ-Al2O3, and CoPd0.093/γ-Al2O3 catalysts as optimal compositions in respective series. Out of these optimal compositions, CoPt0.034/γ-Al2O3 bimetallic catalyst exhibited maximum performance for hydrogen generation from hydrazine decomposition as well as for electro-oxidation of hydrazine. CoPt0.034/γ-Al2O3 catalyst presented 100% H2 selectivity with TOF of 190 h-1, and activation energy of 29 kJ mol-1. All bimetallic catalysts also showed robust electrocatalysis and presented good peak current response for electro-oxidation of hydrazine. These results reflected better alloying effect between Co and Pt metals in addition to presence of more active sites and better metal dispersion. The electroanalytical activity was in the order of: CoPt0.034/γ-Al2O3 > CoPd0.093/γ-Al2O3 > CoIr0.081/γ-Al2O3 > CoRu0.11/γ-Al2O3, with peak current values of 183.2 μA, 59.4 μA, 50.3 μA, and 46.1 μA, respectively. The maximum performance of the optimal catalysts can be attributed to tuning of catalyst’s properties by synergistic effect of two metals, better metal dispersion, metal-support interactions besides the excellent features of γ-Al2O3 granular support as confirmed by XRD, H2 chemisorption, BET, SEM, TEM, TPR and TPO analyses. In addition, noble metals in low contents promoted the activity and selectivity tremendously, and were quite suitable for making the process cost effective for selective decomposition of hydrazine, a toxic material into clean future energy fuel (H2 + N2).
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

تازے زخم جگر دے ہو گئے

نہیں اے سجن میرے پاس
ڈاہڈا ہویا جی اداس
ساڈا سجن بے پروا
دکھیاں دا نہیں کوئی احساس
دکھاں درداں توں نہیں ڈردے
آیا غم جنھاں نوں راس
اندر ہڈیاں دے دھوں دھکھیا
اتوں رہ گیا خالی ماس
اوتھے بہہ کے حقہ پیواں
جتھے چلے تیرا خراس
لے جا پیار حیاتی میری
تیرا وعدہ میرا پاس

Socio-Cultural Analysis of Moral Ethics Syllabi at Under-Graduate Level to Manage the Blasphemy Issue in Pakistan

In the context of blasphemy issue, the present study examines the socio-cultural elements in the Moral Ethics syllabi functional at the different universities of Pakistan. As per our hypothesis, ME syllabi lack some important socio-cultural elements responsible for handling hate crimes, especially the issue of blasphemy. For testing the proposed hypothesis, available ME syllabi were collected from the official websites of different universities. Collected ME syllabi were examined through the method of content analysis. After examining literature review, necessary socio-cultural factors (SCFs) were listed and the selected syllabi were evaluated through this list of SCFs. Our study findings endorse the primary hypothesis that majority of universities has adopted the foreign model of ME syllabi without adapting them according to indigenous social and cultural needs. Additionally, the most important SCFs; knowledge of blasphemy laws (KBL) and real-life dilemmas (RLD), are mostly absent in the existing ME syllabi.

Optimal Homotopy Asymptotic Method to Solution of Partial Differential Equations

Nonlinear Differential equations are of major importance in different fields of science and engineering. For complicated nonlinear problems exact solutions are not available and alternate way is to use numerical methods, Iterative methods or analytical techniques of perturbation. Numerical methods use discretization a have slow rate of convergence. Iterative methods are sensitive to initial conditions and in case of high nonlinearity they do not yield converged results. In perturbation methods small parameter is applied on the equation and hence cannot be applied for high nonlinear problems as they do not have small parameter. One of domain type methods is known as OHAM. This method is free from small parameter assumption and do not need the initial guess. The proposed method provides better accuracy at lower-order of approximations. Moreover the convergence domain can be easily adjusted. In this thesis OHAM is implemented for solution linear and nonlinear tenth order ODEs. Then its effectiveness and generalization is shown to a nonlinear family of PDEs, including Burger, Fisher, Burger’s–Huxley, Burger’s–Fisher, MEW and DGRLW equations. The results of the proposed method are compared with that of DTM, VIM, ADM, HAM and HPM, which reveal that OHAM is effective, simpler, easier and explicit. Apart from application to PDEs, OHAM is applied to couple system of PDEs. The coupled WBK, ALW, MB systems are used as test examples and results are compared with those obtained by HPM. OHAM is implemented to DDEs as well, and solution of MKdV lattice equation is presented for the illustration of proposed technique. The results are compared with HAM and HPM. In all cases the results obtained by OHAM are in close agreement with the exact solution and reveal high accuracy.