Development And Characterization Of Zeolitey From A Nigerian Local Raw Material

ABSTRACT

Zeolites are important chemical materials used in chemical processes. The

manufacture of the materials usually involves the use of expensive chemicals. This study

involves the use of Elefun Nigerian Kaolin (ENK) as precursor material for the development

of zeolite Y. The synthesis of zeolite Y was successful following a sequence: collection of raw

kaolin clay from Elefun area of Ogun state, Nigeria; subjecting it to, calcination, partial

dealumination and final hydrothermal synthesis. The raw clay was refined using

sedimentation technique to recover 98 percent kaolin. Both conventional and novel methods

of metakaolinization technique were used to convert kaolin into the reactive metastable

phase. Amorphous metakaolin was obtained at a temperature of 850oC at residence time of 6

hours. The percentage of the alumina in the metakaolin was reduced through reaction with

sulphuric acid to give Silica/Alumina molar ratio of 4.7 after ageing for between seven and

nine days. The unique procedure of gel formation and Crystallization to NaY zeolite was

achieved after 24hours at 100oC. The NaY zeolite was modified by ion exchange process to

give a more acidic zeolite HY with improved Bronsted active acid sites.

The synthesised Zeolite HY was characterized and confirmed through the XRD pattern and

the silica/alumina ratio of about 3.62 using XRF, the results were corroborated with the

analytical results from both SEM (Scanning Electron Microscope) and BET (Brunauer,

Emmet and Teller). The activity of the synthesised zeolite Y was confirmed. It compared

favourably to the market commercial brand through its very similar conversion in the

cracking reactions of cyclohexane and Gas Oil to lighter products when tested in NNPC

Kaduna Refinery Laboratory.

Keywords: Zeolite-Y, metakaolinization, dealumination, hydrothermal, metastable phase,

Bronsted, microkinectic.