توصيفگر ها :
آلومينيوم فسفات , آلومينا , زيست توده , آلكيل لوولينات , سيستين , حسگر نشري
چكيده انگليسي :
In the first section of this thesis, we have focused on the synthesis and characterization of the Alumina and phosphorus-alumina with different morphologies by the sol-gel method. The morphology, structure, size, phase composition, acidic properties, and thermal behavior were examined by FESEM, TEM, XRD, FT-IR, BET, EDS, NH3-TPD, and TGA-DTA, respectively. It can be found that the morphology of alumina can change from worm-like to spherical by using acetonitrile / 2-octanol solvent mixture and by modifying the synthesis steps. Also, the semi-crystalline structure of γ-alumina was changed to amorphous with improved surface area (from 150 to 229 m2g-1). The addition of phosphorus pentoxide to amorphous alumina with the ratios of 1:9, 2:8 and 1:1 reduced the surface area of the catalyst after calcination from 229 to 129, 16 and 39 m2g-1, respectively. With the increase of phosphorus/aluminum ratio and an increase in calcination temperature, the structure of phosphorus-alumina transformed from amorphous to crystalline. The reactivity and selectivity of 2-octanol over these composites were monitored using GC and GC-mass analyses.
In the second section of this thesis, an easy and effective catalytic method for direct conversion of xylose to BL has been proposed, which has various steps such as transfer hydrogenation process and acid-catalyzed as a cascade model. Organic intermediates, like n-butyl levulinate, have a widespread application, especially in organic synthesis. Thus, direct synthesis of n-butyl levulinate from xylose was investigated over the mesoporous zirconium silicate catalysts (KITZx (X=20,10)). The catalysts were identified through various methods like FESEM, EDS, XRD, FT-IR, nitrogen adsorption-desorption, ICP-AES, and NH3-TPD). An integrated catalytic protocol includes dehydration, and alcoholysis led to the selective formation of n-butyl levulinate and gave a yield of 87.7% over KITZ20 under optimal conditions. Various reaction parameters, for example, the effect of temperature, reaction time, the influence of the catalyst, and the amount of xylose were investigated. The spent catalyst can be effectively recovered after the thermal regeneration of KITZ20 and has good reusability.
In the last section of this thesis, we have focused on the design and synthesis of the new chiral cystine based chemo sensor Cys(imid)2. These chemo sensors show high selectivity and sensitivity toward Fe3+with low detection limits of 42.1 nM (in DMSO), respectively. The fluorescence turn-off recognition of Cys(imid)2 for detection of Fe3+ is attributed to the paramagnetic properties of iron and cleavage of the S–S bond on the coumarin unit of the chemo sensor, respectively. These chemo sensors were prepared in a one-step synthesis via amidation between acid (imide acid) and amine (L-cystine dimethyl ester dihydrochloride).
Moreover, Cys(imid)2 as an optical chemical sensor show very high sensitivity and selectivity for the detection of Fe3+ cation in DMSO solvent, respectively.
