Organic template free synthesis of ZSM11 from kaolinite clay

Abstract

Synthesis of zeolitic materials from mineral ores, encounter serious challenges due to the presence of inherent impurities with the tendencies of inhibiting formation of desired products. Structure directing agent (SDA) though helps to mitigate this effect, but impact negatively on the environment. Zeolite ZSM11 is a promising catalyst that finds application in area not limited to benzene alkylation, gasoline formation from methanol, conversion of low density polyethene into hydrocarbon, etc. Accordingly, this work present successful synthesis of zeolite ZSM11 from kaolinite clay, seeded with NaY type zeolite and aged for 3-11 days, in an organic template free condition. The used kaolinite clays were sourced from two different mines in Nigeria, namely; Kankara and Onibode. They were both subjected to beneficiation, calcinations, dealumination and the gels formed, had molar composition of 9Na2OX30SiO2XAl2O3X225H2O. The raw, intermediate and final products were fully characterized using XRD, XRF, BET and SEM/EDX. The prominent XRD peaks for ZSM11 were noticed for Kankara based sample aged for 11 days with seeding/dealuminatedmetakaolin ratio of 0.2wt% having increased crystallinity and purity as crystallization time increases. Seeding/metakaolin ratios of 0.1, 0.15, 0.25 and 0.3 wt% led to formation of composite material, excluding ZSM11. The morphological analysis gave the shape attributed to ZSM11 and the specific surface area was determined to be 412 and 450m 2 /g, for Kankara and Onibode based products, respectively.

Immobilization of thermostable exo-inulinase from mutant thermophilic Aspergillus tamarii-U4 using kaolin clay and its application in inulin hydrolysis

“…This will in turn have a low cost effect on the immobilization technique as opposed to the use of expensive synthetic materials that are not readily available. Furthermore, Kaolin is reported to have reduced susceptibility to microbial attack compared to wide range of carriers reported in [10] .…”

“…The use of naturally occurring materials as support is preferred to synthetic ones, hence the choice of kaolin clay for immobilization in this study. It is also reported to possess appropriate functional groups necessary for enzyme support [10] . Furthermore, the physiological inertness, non-toxic property coupled with cheap and ready availability of kaolin makes it a potential material for enzyme immobilization.…”

“…Kaolin clay was first beneficiated as described below [9] , [10] . Clay lumps were crushed and screened with a 2 mm sieve.…”

“…Immobilization by adsorption using clay was achieved using a modified method of Ajayi et al [10] .Ten grams (10 g) of the beneficiated, calcined, dealuminated and acid activated clay sample was mixed with 20 mL of inulinase (containing 50–150 units) in 100 ml of 0.2 M sodium acetate (pH 6.0) in a beaker with constant stirring of the clay sample and the solution was then allowed to settle for 24 h. The top solution was decanted and the resulting thick clay immobilized-inulinase was collected, dried at room temperature for a period of 24 h using Whatman No 1 Filter paper. The immobilized inulinase was washed with 50 mL of n-hexane to remove any fatty material and other artifacts which could interfere with the enzyme activity and latter dried at room temperature using Whatman No 1 Filter paper.…”