Synthesis of Hierarchical SAPO‐5 & SAPO‐34 Materials by Post‐Synthetic Alkali Treatment and Their Enhanced Catalytic Activity in Transesterification

Abstract

SAPO‐5 and SAPO‐34 materials were modified using post‐synthetic alkali treatment, which results in the formation of hierarchical SAPO‐5 and SAPO‐34 materials. To test the generation of mesoporosity, the modified materials were thoroughly characterized using XRD, FE‐SEM, TGA, ICP‐OES, and N2 adsorption/desorption techniques. Alkali treated SAPO‐5 and SAPO‐34 materials were utilized for the model reaction triacetin transesterification, under optimized conditions by varying the catalyst amount and reaction time: 90 % triacetin conversion with 66 % methyl acetate yield was achieved using modified SAPO‐5 catalyst, whereas 68 % triacetin conversion with 37 % methyl acetate yield was achieved using modified SAPO‐34 catalyst. The alkali treated SAPO‐5 catalyst was stable up to the 4th cycle.

Synthesis of Hierarchical Silicoaluminophosphate (SAPO) Molecular Sieves by Post‐Synthetic Modification and Their Catalytic Application

“…Microporous SAPO‐34 material was synthesized using TEAOH (tetraethyl ammonium hydroxide) as template using synthesis procedure available from literature with molar gel composition of 1.0Al 2 O 3 : 1.0P 2 O 5 : 0.6SiO 2 : 1.0SDA : 40H 2 O [46–47] . Aluminum iso‐propoxide (SDFCL, 97 %) and o‐phosphoric acid (Merck, 85 %) were used as sources of aluminum and phosphorous.…”

“…Microporous SAPO-34 material was synthesized using TEAOH (tetraethyl ammonium hydroxide) as template using synthesis procedure available from literature with molar gel composition of 1.0Al 2 O 3 : 1.0P 2 O 5 : 0.6SiO 2 : 1.0SDA : 40H 2 O. [46][47] Aluminum iso-propoxide (SDFCL, 97 %) and o-phosphoric acid (Merck, 85 %) were used as sources of aluminum and phosphorous. In a typical procedure, appropriate amount of aluminum iso-propoxide (SDFCL, 97 %) and half of milliQ water was taken in beaker and stirred at the room temperature to form a homogenous mixture.…”

“…A similar procedure was followed to synthesize SAPO-5 but using TEA (triethylamine, Sigma Aldrich, 40 %) as a template. [46][47] The molar ratio of the chemicals for preparing SAPO-5 was 1.0Al 2 O 3 : 1.0P 2 O 5 : 0.6SiO 2 : 1. 0SDA : 40H 2 O.…”

“…Alkali Treatment: Synthesized SAPO-34 and SAPO-5 materials were modified using a mixture of NaOH (Finar, 97 %) and TPAOH (Tetra propyl ammonium hydroxide, Sigma Aldrich) solution through post-synthetic method. [47] In a typical procedure, the materials were stirred with a mixture of 100 ml of 0.1 M NaOH and 20 ml of 1.0 M TPAOH solution at 70 °C for five hours. Finally, the product was filtered using deionized water and dried at room temperature.…”

Synthesis and Applications of SAPO‐34 Molecular Sieves

“…Kasyanov et al [101] introduced a novel mesoporous molecular sieve preparation technology, which introduced the surfactant cetyltrimethylammonium bromide in the alkali treatment process, which not only increased the mesoporous ratio, but also the Y-type molecular sieves have high crystallinity and yield. Divya Jadav [102] found that alkali treatment of SAPO materials leads to the formation of mesoporosity with enhanced catalytic activity in the transesterification of triacetin.…”