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SO2-4/TiO2-SiO2 Mixed Oxide Catalyst, I: Synthesis, Characterization, and Acidic Properties.
1Regional Research Laboratory (CSIR), Bhubaneswar-, Orissa, 751013, India
Journal of Colloid and Interface Science
|July 9, 1999
Summary
Sulfate-doped titania-silica mixed oxides were synthesized and characterized. These novel materials exhibit enhanced acidity, showing promise as catalysts for alcohol conversion and cumene cracking reactions.
Area of Science:
- Materials Science
- Catalysis
- Surface Chemistry
Background:
- Mixed oxides offer tunable properties for catalytic applications.
- Sulfation can introduce or enhance acidic sites on oxide surfaces.
Purpose of the Study:
- To synthesize and characterize sulfate-doped titania-silica mixed oxides.
- To evaluate their catalytic activity in alcohol conversion and cumene cracking.
Main Methods:
- Preparation of titania-silica gel via hydrolysis of TEOS and TBOT.
- Sulfation by immersion in sulfuric acid, followed by drying and calcination.
- Characterization using XRD, FT-IR, BET, and Hammett indicator method.
- Catalytic activity testing in fixed-bed and micropulse reactors.
Main Results:
- Amorphous titania-silica structure with crystallization initiated by sulfation.
- Presence of bridged and normal hydroxyl groups on the surface.
- Surface area around 50 m²/g, minimally affected by sulfation.
- 4 wt% SO2-4/TiO2-SiO2 exhibited acid strength greater than concentrated sulfuric acid.
- Low acetone selectivity in 2-propanol conversion suggests weak basic sites.
- Methanol conversion indicated parallel and consecutive dehydration pathways.
- Strong correlation observed between cumene cracking activity and catalyst acidity.
Conclusions:
- Sulfate doping effectively enhances the acidity of titania-silica mixed oxides.
- The synthesized materials demonstrate potential as solid acid catalysts.
- Catalytic performance is directly linked to the surface acidity of the doped materials.