Scalable Synthesis of Uniform Mesoporous Aluminosilicate Microspheres with Controllable Size and Morphology and High Hydrothermal Stability for Efficient Acid Catalysis

Abstract

Mesoporous aluminosilicates are promising solid acid catalysts. They are also excellent supports for transition metal catalysts for various catalytic applications. Synthesis of mesoporous aluminosilicates with controllable particle size, morphology, and structure, as well as adjustable acidity and high hydrothermal stability, is very desirable. In this work, we demonstrate the scalable synthesis of Al-SBA-15 microspheres with controllable physicochemical properties by using the microfluidic jet-spray-drying technology. The productivity is up to ∼30 g of dried particles per nozzle per hour. The Al-SBA-15 microspheres possess uniform controllable micron sizes (27.5−70.2 μm), variable surface morphologies, excellent hydrothermal stability (in pure steam at 800 °C), high surface areas (385−464 m 2 /g), ordered mesopore sizes (5.4−5.8 nm), and desirable acid properties. The dependence of various properties, including particle size, morphology, porosity, pore size, acidity, and hydrothermal stability, of the obtained Al-SBA-15 microspheres on experimental parameters including precursor composition (Si/Al ratio and solid content) and processing conditions (drying and calcination temperatures) is established. A unique morphology transition from smooth to wrinkled microsphere triggered by control of the Si/Al ratio and solid content is observed. The particle formation and morphology-evolution mechanism are discussed. The Al-SBA-15 microspheres exhibit high acid catalytic performance for aldol-condensation reaction between benzaldehyde and ethyl alcohol with a high benzaldehyde conversion (∼56.3%), a fast pseudo-first-order reaction rate (∼0.1344 h −1 ), and a high cyclic stability, superior to the commercial zeolite acid (H-ZSM-5). Several influencing factors on the catalytic performance of the obtained Al-SBA-15 microspheres are also studied.

Hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene over NiMo supported on yolk-shell silica catalysts with adjustable shell thickness and yolk size

“…Small-angel XRD patterns of YxSy and Al-YxSy are presented in Figure 1A and Figure 1B. From Figure 1A, all the YxSy samples exhibit a diffraction peak in the 2θ range of 1.5°-3°, indicating that the ordered mesopores are presented in the yolk-shell mesoporous materials and the space group of these supports can be attributed to P6mm [32,33].The sizes of shell and yolk become smaller with the gradual increasing of TMB content and the corresponding diffraction peak also shifts to a lower angle with the thinning of yolk-shell structure.…”

Sustainable Synthesis of Epoxides from Halohydrin Cyclization by Composite Solid-Based Catalysts

“…Epoxides are important raw materials in the chemical industry for the synthesis of glycols, epoxy resins, polyethers, etc. − They are commonly synthesized through the oxidation of olefins by molecular oxygen or peroxides in the presence of metal catalysts. Epoxides can also be synthesized through the dehydrohalogenation of halohydrins through base-driven S N 2 substitution. − However, due to the general consensus of pursuing a sustainable green process, new methods are continuously developed to replace the petrochemical-based routes. − Glycerol, an oversupplied byproduct from biodiesel production, − has therefore been considered as an alternative feedstock for the production of epoxides. − The simplest route to achieve the set target would start with the halogenation of one of the hydroxyl groups to form chloro-propanediol under the presence of an organic acid catalyst such as acetic acid. Then, the base-driven S N 2 substitution can be applied to carry out the ring-closing epoxidation.…”

Obtaining of Mesoporous Aluminosilicates with High Hydrothermal Stability by Composite Organic Templates: Utility and Mechanism

“…In Li’s study, microspheres of Al-containing SBA-15 with controlled characteristics were obtained by employing the spray-drying technique by microfluidic jet. However, in this process, yield of products was 30 g/h, and the surface area was 385–464 m 2 /g in their strategy.…”

“…In Li's study, 19 process, yield of products was 30 g/h, and the surface area was 385−464 m 2 /g in their strategy. In Tirumala's study, 20,21 an disorder−order transition could be obtained by the selective miscibility of poly(acrylic acid) (PAA) with EO segments of P123.…”