The Use of Cellulose Nanocrystals to Support Ca(OH)2 Nanoparticles with Diatomite Incorporation in Sulphur Capture at Low Temperatures: Optimisation and Modelling

Cellulose is a renewable resource that can be used to develop sorbents for dry flue gas desulphurisation processes. In this study, nanoparticles of hydrated lime (Ca(OH)₂) were impregnated onto cellulose nanocrystals (CNCs) using a co-precipitation technique. The Ca(OH)₂/CNCs composite was then mixed with diatomite and hydrated. Fourier transform infrared and X-ray diffraction confirmed the presence of CNCs in the synthesised sorbent. BET (Brunauer–Emmett–Teller) surface area demonstrated an increase in the reaction area (58.564 m²/g) compared to the commercial hydrated lime (18.019 m²/g). Response surface methodology was used for optimisation tests and to statistically model the experimental variables, including hydration time, hydration temperature, diatomite to Ca(OH)₂ ratio, sulphation temperature, and inlet sulphur concentration. A quadratic model from the analysis of variance (ANOVA) evaluation found diatomite to Ca(OH)₂ ratio as the model term with the most considerable influence towards both sulphation and conversion, with the highest outcome achieving 54% sulphation and 42% conversion.