Textural mesoporosity and opening frame network of mesoporous MOR zeolites synthesized under intensifying perturbation conditions

Several amorphous, composite and crystalline mesoporous aluminosilicates were synthesized via perturbation routes and using combined templates. By powder X-ray diffraction, nitrogen adsorption at 77 K, transmission electron microscopy, ammonia temperature-programmed desorption and thermogravimetric–differential thermal analyses, intensifying perturbations impacted on product phase, mesoporosity and textural feature were investigated according to synthesis modes of T1(t1) → T2(t2), wherein a cooperative alteration to Ti(ti) resulted in a variation in perturbation intensity (ΔTi(ti), i = 1, 2). As a consequence, the perturbations imposed on synthesis conditions caused significant changes in mesostructure, crystallinity and acidity of resulting materials. The structural difference between two types of composite mesoporous materials was the transformation from an inhomogeneous phase into a hypocrystalline phase. Mesoporous mordenites (MOR) with a hierarchy of pores exhibited crystalline mesoporous textures featuring of bulky structural defects. Among them, opening frames per se observed in mesoscale were of crystallized mesoporous MOR matrixes. These results confirmed the important role of perturbation intensity taken as coupling kinetic factors in controlling over the solid crystalline and additional mesoporous properties. Upon TG weight loss rates (%) and DTA peak temperatures for total combustibles and derived cokes, these alkylammonium and aliphatic amines captured were strongly restricted by framework charges and irregular mesopore geometries of the MOR zeolites, and therefore partially transformed into cokes hardly to remove. Additionally, there was a prominently linear response to the correlation between specific pore volume and total combustible weight loss rate for all mesoporous materials.

Graphical abstractMorphological character and textural change of various mesoporous materials synthesized via intensifying perturbation imposed on crystallization temperature and period were diagrammatized to elucidate a course of disordered mesostructure degeneration and hence crystalline mesoporous MOR zeolite formation, wherein an inserted graph was used in illustration of a linear response to the correlation between specific mesopore volume and total combustible weight loss rate for whether composite or crystalline mesoporous materials, while the derived coke content depended remarkably on crystalline nature, rather than total combustible content, i.e. the absorbing capacity.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Demonstration of approaches on perturbation synthesis of mesoporous mordenites. ► Influence of intensifying perturbation condition on crystalline mesoporous texture. ► Crystalline mesopore formation followed ordered mesostructural degeneration. ► Hierarchically porous MOR zeolites and opening frame textures in mesoscale. ► Batch TG–DTA analyses described interplays between templates and aluminosilicates.