Silica gel alumina is an efficient moisture control adsorbent used for drying compressed air and acetylene as well as protecting other adsorbents and catalysts from moisture damage.
Structure of Silica Gel | Mercury Porosimetry The structural properties of silica gel can be evaluated through N2 adsorption at 77 K and mercury porosimetry; surface chemistry analysis through 1H-NMR spectra can also provide valuable data.
High Adsorption Capacity
Silica gel absorbs large quantities of water, making it one of the most efficient desiccants available. With such an expansive capacity for water absorption, silica gel has proven itself as an indispensable desiccant in protecting compressors with lower dew points as well as being used as a dehumidifier and dryer in moisture-sensitive chemical processes like electronics production. Furthermore, it can even be used as a regenerative drying agent protecting pneumatic equipment from moisture-related issues.
Silica gel’s structural properties and surface chemistry can be assessed using several established techniques, including N2 adsorption at 77 K and mercury porosimetry. Unfortunately, however, silanol groups present on its surface can be challenging to distinguish and quantify using these approaches. Pretreatment temperatures have proven effective in solving this problem. By pretreating Fuji Davison RD silica gel with different temperatures, one has been able to observe its effect on structure and surface chemistry; N2-adsorption, 29Si NMR spectroscopy measurements as well as TGA measurements were all utilized as tools to study how pretreatment affects structure and silanols on surfaces.
As temperatures rose, geminal OH groups decreased while isolated and vicinal ones increased, as energy levels of 95kJ/mol-1 were assigned for silanol groups, one for isolated ones and another one corresponding to those located near geminal ones.
Low Chemical Reactivity
Silica gel alumina is known for being inert under changing temperatures and pH conditions, making it an excellent long-term choice. Furthermore, its physical adsorption mechanism works effectively in various environments.
Chemically stable and flameproof, aluminum is insoluble with most solvents – all qualities which make it an ideal material for industrial driers and desiccant applications.
Silica alumina’s low chemical reactivity is due to its abundance of free and vicinal silanol groups on its surface, which allows it to effectively adsorb and retain water molecules. Furthermore, its low surface energy and high porosity make it an excellent candidate for gas absorption.
Scheme 2 shows an easy process for the production of amino group-ion liquid functionalized silica gel sorbents (Scheme 2) [51]. First, acid solution is applied to activate silanols on the surface of sorbent, followed by covalently bonding synthetic amino group-ion liquids into it using covalent bonds; finally it’s washed and dried after completion of treatment.
N2 isotherms and adsorption calorimetry are used to characterize the energetic characteristics of grafted silica-IL gels, with results showing good approximations between calculated total silanol numbers and those determined from TGA measurements. Furthermore, high load-dependent heats of adsorption for pyrrolidine suggest that their overall adsorption behavior involves silanol groups associated with adjacent surfaces as well as those located elsewhere within these sorbents.
Versatility
Silica gel alumina’s unique mesoporous structure allows it to interact effectively with various gases and liquids, including gases such as nitrogen. Furthermore, its physical adsorption mechanism enables it to effectively remove moisture in environments that would be difficult or impossible to treat using traditional desiccants.
Alumina boasts exceptional water-retention capacities for air drying and acetylene separation applications, making it a popular choice among industrial users. Alumina’s low particle emission rate also makes it suitable for environmental cleanup applications.
Another significant advantage is silica gel alumina’s versatility when working with different acids, bases, and solvents – making it ideal for many pharmaceutical and petrochemical industries, particularly oil catalytic cracking applications and chemical synthesis processes.
Yamtop offers high-grade alumina in several forms and sizes, such as micronized silica alumina and granular silica alumina, both featuring excellent dissolution properties that make them invaluable tools in chemical isolation applications. Rapid dissolution rates make alumina an appealing alternative; in fact, many silica users have switched over.
Applications
Silica gel alumina’s low chemical reactivity and high adsorption capacity have made it suitable for many different applications, from desiccant use in protecting electronic components from moisture degradation, to its use as a catalyst carrier in refining processes.
Silica gel alumina can also serve as an effective drying agent, typically packaged in small paper or cloth sachets and included with commercial products like electronics to protect them against moisture destruction. Furthermore, air drying systems often employ silica gel alumina as it efficiently extracts moisture from compressed air which reduces energy requirements when compressing dry air.
In order to understand the adsorption mechanism of an alumina gel, N2-adsorption measurements, 29Si and 1H NMR as well as calorimetry with pyrrolidine were utilized. Based on these data, a model was devised that assigned adsorption energies directly with silanol groups found on vicinal surfaces; its values approximate those found through TGA measurements.