Synthesis and characterization of heterogeneous catalysts via silica obtained from Iraqi rice Husks
Other Title(s)
تحضير و تشخيص محفزات غير متجانسة عن طريق السليكا المستحصلة من قشور الرز العراقي
Dissertant
al-Hamidawi, Haydar Hamid Muhsin
Thesis advisor
al-Husni, Thana Jafar Muhammad
Comitee Members
Suhyl, Falah Sharif Abd
Mahdi, Bassim I.
Sarhan, Basimah Muhsin
Amin, Siham Tawfiq
University
University of Baghdad
Faculty
College of Science
Department
Chemistry Department
University Country
Iraq
Degree
Ph.D.
Degree Date
2012
English Abstract
Rice husks (RH) are the hard protecting coverings of grains of rice.
The main function of rice husk is protecting rice during the growing season.
These (RH) pose as a waste in large quantities by plants producing rice.
In Iraq have not given any attention to this material, on the contrary, burn to get ride of it leading to a significant pollution.
It has been observed through the literature that rice husk ash (RHA) usually containing around 95% silica with small amounts of inorganic salts after complete combustion at 800 °C for 6 h.
It is used by the steel industry and concrete manufacturing, as an excellent insulator and as a catalyst support and heterogeneous catalyst for several catalytic reactions.
Sodium silicate from RHA was transformed to functionalized with 3- (chloropropyl)triethoxysilane (CPTES) and 3–(mercaptopropyl)triethoxysilane (MPTES) via a simple sol–gel technique in a one-pot synthesis to yield silica with chloro and thio groups on its surface.
The products were labeled as RHACCl and RHACSH.
Dithiooxamide, bis (dithiooxamide) palladium(II) chloride, pphenylenediamine and dichlorodiaquabis(p-phenylenediamine)copper(II) were immobilized onto RHACCl via nucleophilic substitution reaction to yield heterogeneous catalyst; These catalysts were labelled as RHAC-DTO, RHACPd( DTO)2, RHAC-p-PDA, and RHAC-Cu(p-PDA)2, respectively.
While chloroacetic acid and ethyl chloroacetate were immobilized onto the RHACSH to yield RHACS-ACOH and RHACS-ACOEt.
The BET surface area of RHACCl and RHACSH were found to be 633 and 331.61 m2 g-1, while the specific surface of RHAC-DTO, RHAC-p-PDA, RHAC-Pd(DTO)2, RHACCu( p-PDA)2, RHACS-ACOH and RHACS-ACOEt were found to be 9.75, 145, 70.83, 60.15, 66.13 and 269.35 m2 g-1, respectively.
Thermogravimetric analyses (TGA-DTA) for the RHACCl, RHACSH, RHAC-DTO, RHAC-p-PDA, RHACPd( DTO)2 , RHACS-ACOH and RHACS-ACOEt indication that the physical adsorb water was lost between 30-160 °, while the residual parts of material decomposed up to 300 °C.
The 29Si MAS NMR of RHACCl showed the presence of T2, T3, Q3 and Q4 silicon centres, while the T1, T2, T3, Q2, Q3 and Q4 silicon centres was present in RHACSH.
The 13C MAS NMR showed that the RHACCl had three chemical shifts at 10.37, 26.70 and 47.69 ppm, which was attributed to the three carbon atoms of the CPTES moiety.
RHACSH had two signals at 43.29 and 59.49 ppm instead of the expected three signals.
This was due to the superimpose of the two signals on each other.
According to these results and other results obtained by using CHNS analysis and FT-IR spectra, the structures of RHAC-DTO, RHAC-Pd(DTO)2, RHAC-p-PDA, RHAC-Cu(p- PDA)2, RHACS-ACOH and RHACS-ACOEt were suggested.
X-ray diffraction technique showed that the catalysts have amorphous face, while the scanning electron microscopy (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM) techniques were proved that the catalysts have spherical nano particles.
Catalytic activity for RHAC-DTO and RHAC-p-PDA were investigated in the esterification reaction of acetic acid with ethyl alcohol to produce ethylacetate.
The optimum conditions of the esterification over RAHC-DTO and RHAC-p-PDA were found to be 6h reaction time, 1:1 mole ratio, 0.2 g the catalyst mass and 85 °C as reaction temperature.
The conversion of ethyl alcohol over RHAC-DTO is higher than that the RHAC-p-PDA, while the homogenous DTO and p-PDA gave a lower conversion than the heterogeneous RHAC-DTO and RHAC-p-PDA.
Main Subjects
Topics
No. of Pages
153
Table of Contents
Table of contents.
Abstract.
Abstract in Arabic.
Chapter One : Introduction.
Chapter Two : Experimental part.
Chapter Three : The characterization of RHACCl and its derivatives RHAC-DTO, RHAC-p-PDA, RHAC-Pd(DTO)2 and RHAC-Cu(p-PDA)2.
Chapter Four : The characterization of RHACSH and its derivatives RHACS-ACOH and RHACS- ACOEt.
Chapter Five : Esterification of acetic acid with ethyl alcohol over RHAC-DTO and RHAC-p-PDA.
Chapter Six : Conclusions and future prospects.
References.
American Psychological Association (APA)
al-Hamidawi, Haydar Hamid Muhsin. (2012). Synthesis and characterization of heterogeneous catalysts via silica obtained from Iraqi rice Husks. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-600531
Modern Language Association (MLA)
al-Hamidawi, Haydar Hamid Muhsin. Synthesis and characterization of heterogeneous catalysts via silica obtained from Iraqi rice Husks. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad. (2012).
https://search.emarefa.net/detail/BIM-600531
American Medical Association (AMA)
al-Hamidawi, Haydar Hamid Muhsin. (2012). Synthesis and characterization of heterogeneous catalysts via silica obtained from Iraqi rice Husks. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-600531
Language
English
Data Type
Arab Theses
Record ID
BIM-600531
