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Keywords = peptizing HNO3

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27 pages, 10348 KB  
Article
Formulation of Shaped ZSM–5/Al2O3 Composites: Comparison of Pseudoboehmite and Nitrate-Derived Aluminum Binders
by Alma Massenova, Ivan Torlopov, Kenzhegul Rakhmetova, Alexandr Sass, Ardak Zhumakanova, Makpal Malgazhdarova and Arlan Abilmagzhanov
Catalysts 2026, 16(8), 751; https://doi.org/10.3390/catal16080751 - 21 Aug 2026
Viewed by 232
Abstract
This study focuses on the shaping of ZSM–5-based granules using conventional pseudoboehmite as well as aluminum hydroxynitrate precursors obtained by partial thermal treatment of Al(NO3)3·9H2O. The starting materials and nitrate-derived precursors were characterized by X-ray diffraction, thermal [...] Read more.
This study focuses on the shaping of ZSM–5-based granules using conventional pseudoboehmite as well as aluminum hydroxynitrate precursors obtained by partial thermal treatment of Al(NO3)3·9H2O. The starting materials and nitrate-derived precursors were characterized by X-ray diffraction, thermal analysis, infrared spectroscopy, scanning electron microscopy, and low-temperature nitrogen adsorption. Model pseudoboehmite systems were used to evaluate the effects of moisture, peptization equivalent, and HNO3 concentration in the initial liquid portion on pore volume, apparent density, shrinkage, and axial and radial crushing strength. Acid peptization showed a strongly non-linear effect: small HNO3 additions increased strength and densification, whereas excess acid promoted structural heterogeneity and granule disintegration during thermal treatment. Even at constant moisture and total acid dosage, strength depended markedly on the initial peptizer concentration. In unpeptized ZSM–5/pseudoboehmite composites, increasing zeolite content reduced pore volume but increased density and strength, indicating formation of a more compact framework. Aluminum hydroxynitrate precursors enabled effective shaping of ZSM–5-containing pastes, demonstrating their potential as alternative binder precursors, while the optimized pseudoboehmite systems provided the most favorable overall balance between porosity and mechanical stability. Full article
(This article belongs to the Special Issue Synthesis of Zeolites and Their Applications in Catalysis)
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18 pages, 7008 KB  
Article
Recyclable Aggregates of Mesoporous Titania Synthesized by Thermal Treatment of Amorphous or Peptized Precursors
by Maria Cristina Mascolo and Terry Arthur Ring
Materials 2018, 11(3), 381; https://doi.org/10.3390/ma11030381 - 5 Mar 2018
Cited by 4 | Viewed by 3685
Abstract
Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC2H5)4 or of Ti(OC2H5 [...] Read more.
Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC2H5)4 or of Ti(OC2H5)4 in mixture with 5 mol % Zr(OC3H7)4 at room temperature in the presence of NH4OH as a catalyzing agent. The anatase–rutile ratio, the recyclable aggregates of the nano-sized particles, the mesoporosity, the surface area and the crystallinity of the resulting crystallized products of titania can be controlled by the synthesis parameters including: concentration of ammonia catalyst, stirring time and concentration of the peptizing HNO3, drying method of peptized precursors, calcination temperature, and finally the ramp rate up to the titania crystallization temperature. A broad range of synthesis parameters control the crystal sizes of titania particles produced. This allows catalyst preparation with very different crystal size, surface area, anatase to rutile crystal ratio and various mesoporous structures. Drying by lyophilization of precursors reduce the aggregation of the primary particles giving micro-/macroporous structures. Full article
(This article belongs to the Section Porous Materials)
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