Abstract

Objective As one of the powder preparation methods， the spray drying method offers advantages such as simple operation andhigh production efficiency. This study is conducted to improve the preparation efficiency of porous silica （SiO₂） microspheresand achieve their large-scale production.

Methods The spherical and branched silica sols were passed through a cation exchange resin to remove alkali metal ions， rendering the treated silica sols acidic （pH=2_~3）. Based on the principles of the spray drying technique， the process parameters were set as follows： drying temperature 150 ℃ ， atomization pressure 0. 2 MPa， and feed rate 20 mL/min. After parameter adjustment， the fan， heater， and air compressor were turned on in sequence. Once the temperature reached 150 ℃， the peristaltic pump was switched on to deliver the silica sol into the spray dryer at the preset flow rate. The silica sol was atomized into finedroplets through the atomizer nozzle， which rapidly lost moisture upon contact with hot air in the drying chamber， forming solid SiO₂ particles （porous SiO₂ microspheres）. The dried powder product was collected after passing through the cyclone separator.The morphology and particle size distribution of the microspheres after spray drying were observed via optical microscopy. Their morphology was further examined by scanning electron microscopy （SEM）. The specific surface area， average pore size， and pore volume were measured using the Brunauer-Emmett-Teller （BET） method.

Results and Discussion After spray drying spherical silica sol， the resulting porous SiO₂ microspheres exhibited defects such ascollapse and fracture， and the severity of these defects increased with larger particle sizes of the spherical silica sol. In contrast，short-branched silica sol yielded microspheres with excellent sphericity， with the highest specific surface area reaching up to 789. 51 m²·g⁻¹ and a pore size distribution ranging from 1 to 10 nm. Using short-branched silica sol as a reinforcing agent could improve the sphericity of porous SiO₂ microspheres obtained from spray-dried long-branched silica sol. By adjusting the dosage of short-branched silica sol， the specific surface area， pore size， and pore size distribution of the microspheres could be effectively controlled.

Conclusion For the pressure spray drying processes， the branched silica sol exhibited a higher spherization rate than the spherical silica sol. Porous SiO₂ microspheres produced with branched silica sol as the raw material showed a larger specific surfacearea and a narrower pore size distribution. Short-branched silica sol with smaller diameters produced porous SiO₂ microspheresof good sphericity， large specific surface area， and narrow pore size distribution after spray drying. In contrast， long-branchedsilica sol with larger diameters tended to form porous SiO₂ microspheres that were prone to fracture and incomplete structures.Through blending with smaller-diameter short-branched silica sol， the spherization rate could be improved， while the specific surface area and pore size of the porous SiO₂ microspheres could be tuned.

Keywords：spray drying； porous silica microsphere； silica sol

Get Citation：ZONG Zhihao， PANG Xiangbo， YANG Shaohan， et al. Preparation of porous silica microspheres by spray drying method［J］.China Powder Science and Technology，2026，32（2）：1−11.

Received: 2025-06-13 .Revised:2025-07-30,Online: 2025-11-12.

Funding Project:The research was supported by the National Natural Science Foundation of China （Grant No. 22278174 and 21808079），the Excellent Youth Science Foundation of Shandong Province （Overseas）（Grant No. 2022HWYQ-082），the Mount Taishan Scholar Young Expert Foundation of Shandong Province（Grant No. tsqn202408211），and the Natural Science Foundation of Shandong Province（Grant No. ZR2021MB117）.

DOI：10.13732/j.issn.1008-5548.2026.02.013

CLC No:TQ127.2； TB4                    Type Code: A

Serial No:1008-5548（2026）02-0001-11