The conversion of CO2 into carbon feedstock via CO2 hydrogenation to methane requires a stable catalyst for reaction at high temperatures. Zeolite NaY (abbreviated hereafter as NaY) synthesized from naturally occurring kaolin provides a stable support for Ni nanoparticles. Kaolin can be further dealuminated using sulfuric acid to reduce the Si/Al ratio, but the presence of the remaining sulfur is detrimental to the formation of NaY. The objective of the present study was to synthesize NaY from dealuminated metakaolin, using a method that minimizes the detrimental effects of sulfur, and to investigate the effect of its activity on CO2 methanation. Kaolin from Bangka Belitung, Indonesia, was calcined at 720°C for 4 h to form metakaolin (M) and subsequently treated with sulfuric acid to form dealuminated metakaolin (DM). Excess sulfur was removed by washing with deionized water at 80°C. Zeolite NaY was then synthesized from the M and DM via a hydrothermal method; the relationship between morphology, structural properties, and the catalytic activity of NaY was determined for CO2 methanation at 200–500°C. The presence of excess sulfur following dealumination of metakaolin produced NaY with small surface area and porosity. After Ni impregnation, the synthesized NaY exhibited significant catalytic activity and stability for the reaction at 250–500°C. Analysis by scanning electron microscopy and high-resolution transmission electron microscopy showed the formation of well-defined octahedral structures and large surface areas of ~500 m2/g when NaY was synthesized using DM. Catalytic activity indicated significant conversion of CO2 (67%) and CH4 selectivity (94%) of Ni/NaY from DM in contrast to only 47% of CO2 conversion with 77% of CH4 selectivity for Ni/NaY synthesized from M. Dealuminated metakaolin also produced robust NaY, which indicated no deactivation at 500°C. The combination of well-defined crystallite structures, large surface area, and small Al contents in NaY synthesized from DM helped in CO2 conversion and CH4 selectivity for the reaction at 200–500°C.

Zeolite Y has been synthesized from Kaolin Bangka Belitung as precursor through activation of metakaolin with acid. The synthesis of zeolite Y consist of metakaolinitation, activation metakaolin with sulfuric acid using various concentrations (3, 6, 9, 12, and 15 M), aging, hydrothermal process for 24 hours at 100 °C. The solid products were characterized with X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The result of XRD and FTIR indicated that zeolite Y formed at the variations 3, 6, 9, 12, and 15M. Based on XRD pattern of the results, phase of zeolite P formed at the variation 3M. The surface morphology and ratio of Si/Al of Zeolite Y was analyzed using SEM-EDX. The SEM micrograph of zeolite Y and P with variation of sulfuric acid 3, 6, 9, 12, and 15M like octahedral and sphere form and the ratio of Si/Al of the products based on EDX are 1.7; 1.6; 1.58; 1.64; and 1.59 respectively.

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