Solid Phase ZSM-5 Synthesis from Coal Gasification Coarse Slag

PurposeA novel method is reported for preparing single-phase ZSM-5 molecular sieves by solid-phase, non-caustic soda-mediated synthesis using solid-waste coal gasification coarse slag (CGCS) as a raw material.MethodsInexpensive industrial-grade silica and sodium carbonate decahydrate, as sources of alkali and crystal water, were added to the unpretreated coal gasification slag. The physicochemical properties of the obtained samples were characterised by X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and NH3-temperature-programmed desorption analysis.ResultsReconstruction of the original silicon-aluminium structure is achieved by simply mixing, grinding, and heating the ingredients. Na2CO3·10H2O provides the basic conditions necessary for depolymerisation and reconstruction of the silicon and aluminium, and the crystal water is necessary. The synthesis conditions are mild and solvent-free.ConclusionA novel and green ZSM-5 synthesis method is reported for addressing large-scale accumulation of CGCS. The method improves the reactor utilisation rate compared to the existing approaches and avoids waste liquid water pollution.