Preparation and Evaluation of Precipitated Silica for CO2 Removal

13 Pages Posted: 5 Apr 2021

See all articles by Talal Alhajeri

Talal Alhajeri

Khalifa University of Science and Technology and Research

Mohammad Abu Zahra

Khalifa University

Ahmed AlHajaj

Khalifa University of Science and Technology

Dang V. Quang

Phenikaa University

Date Written: February 14, 2021


In gas separation and purification, adsorption using solid sorbents is very well known as an effective technology for removing acid gases. There are many applications to this technology where grafting functional groups of amines into the pore walls of silica can create a distinct adsorbent type. With this manipulation adsorbents operating conditions, regeneration, selectivity, and stability maybe controlled for a particular application such as the food industry, pharmaceuticals, textile industry, manufacturing, and shown interest in greenhouse gases mitigation.

CO2 adsorption using precipitated silica supported amine is an attractive method for carbon capture technologies due to its high loading capacity, regeneration potential and low cost. H2S removal using silica has shown high loading as demonstrated by (Vaewdaow Jaiboon et al., 2014) at around 50-60wt% with an Si-TRI grafted silica [1]. Simultaneous adsorption with silica has not been extensively studied due to greater modification to the experimental setup which involves using sequential sorption and double stage bed reactors with varying feed temperatures for each species as CO2 generally takes longer to adsorb compared to H2S adding to the complexity of the dual adsorption mechanism.

The purpose of this study is to synthesize precipitated silica from sodium silicate using CO2 as an acidizing agent and then impregnate polyethyleneimine (PEI) to produce CO2 adsorbent experimentally. The novel silica loading and regeneration potential will be evaluated with CO2.

The adsorbent with various PEI contents from 30 to 65 wt% was prepared by a wet impregnation method. The surface area, pore volume and pore size were analysed by a nitrogen adsorption/desorption method. A scanning electron microscope was used to study the structure of the adsorbent, and a Thermogravimetric analysis (TGA) was performed using a Thermogravimetric analyser (SDT Q600). Precipitated silica having surface area of 117.9 m2/ and pore volume of 1.52 cm3/g was synthesized and used for PEI impregnation. The CO2 adsorption performance was examined using a flow Micro Reaction Calorimeter (URC) by flowing pure CO2 into analysis cell under isothermal condition. CO2 adsorption experiments will be conducted at different adsorption and regeneration temperatures to determine optimum operation temperature for CO2 capture.

Preliminary results show an increase in mass of CO2 per gram of adsorbent from 89.8 to 180.04 mg/g as PEI impregnated contents increasing from 30 -60wt%, respectively. Further tests have been carried at various temperatures ranging from 60-90°C and a general increase in loading capacity was observed. When the sample was regenerated at 60°C the adsorption capacity decreased slightly for lower PEI wt% but increased higher than the first trial for higher PEI wt%. in general, with PEI 65wt% the loading of the amine dropped significantly.

The outcome of this research will help strengthen the understanding of precipitated silica subjected to CO2 loading and the translation of the experimental model to a simulation model used to mimic a full-scale adsorption plant. The affinity towards CO2 will aid in the global research endeavour to study different morphologies and their optimum application space.

Keywords: Precipitated Silica, Adsorption, CO2 Loading, Characterization, Pore Volume, Pore Size Distribution, Surface Area

Suggested Citation

Alhajeri, Talal and Abu Zahra, Mohammad and AlHajaj, Ahmed and Quang, Dang Viet, Preparation and Evaluation of Precipitated Silica for CO2 Removal (February 14, 2021). Proceedings of the 15th Greenhouse Gas Control Technologies Conference 15-18 March 2021, Available at SSRN: or

Talal Alhajeri (Contact Author)

Khalifa University of Science and Technology and Research ( email )

Abu Dhabi
United Arab Emirates
0529303003 (Phone)

Mohammad Abu Zahra

Khalifa University ( email )

Abu Dhabi
United Arab Emirates

Ahmed AlHajaj

Khalifa University of Science and Technology

Abu Dhabi
United Arab Emirates

Dang Viet Quang

Phenikaa University

To Huu road, Yen Nghia
Ha Dong district
Hanoi, Hanoi 100803

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