Characterization of Multimodal Silicas Using TG/DTG/DTA, Q-TG, and DSC Methods

Abstract

The formation of hierarchical, multimodal porosity materials with controlled shape and size of pores is the essential challenge in materials science. Properties of silica materials depend largely on different features: crystal structure, dispersity, surface composition, and porosity as well as the method of preparation and possible modification. In this paper, multimodal silicas obtained using different additives are presented. A-50 and A-380 aerosils and wide-porous SiO 2 milled at 300 rpm were used as the additives in the sol stage at 20 • C, the sol-gel stage followed by hydrothermal modification (HTT) at 200 • C, or in the mechanochemical treatment (MChT) process. The characterizations were made by application of N 2 adsorption/desorption, SEM imaging, quasi-isothermal thermogravimetry (Q-TG), dynamic thermogravimetry/derivative thermogravimetry/differential thermal analysis (TG/DTG/DTA), and cryoporometry differential scanning calorimetry (DSC) methods. Results showed that such a one-step preparation method is convenient and makes it possible to obtain multimodal silicas of differentiated porous structures and surface chemistry.

Silicon Radical‐Induced CH4 Dissociation for Uniform Graphene Coating on Silica Surface

“…The TG profile of MPS in Figure S5 (Supporting Information) exhibits weight loss upon heating due to H 2 O desorption (m/z = 18), corresponding to physically bound H 2 O and dehydration reactions between silanol groups (>200 °C) according to Equation 2. [38] In contrast, TMS-MPS shows little weight change from water loss upon heating (Figure 1b), which is in agreement with the FTIR results. In addition, the detected signal of m/z = 75 at temperatures exceeding 300 °C can be ascribed to a typical fragment of hydroxylated TMS, i.e., (CH 3 ) 2 Si-OH + ), as TMS groups on TMS-MPS can react with desorbed H 2 O (Equation 3) or remaining hydroxyl groups (Equation 4).…”

Catalytic nanosponges of acidic aluminosilicates for plastic degradation and CO2 to fuel conversion

“…Sautet et al 45 observed the effect of hydroxylation on the C Q value in their study of γ-alumina. The hydroxyl density of AAS is calculated by the thermal gravimetric analysis (TGA) of the samples using the Boer equation 46 (Supplementary Fig. 14 , Supplementary Table 4 ), and found to be within the range of 5.4 to 13 OH nm −2 .…”

Development of chromium-impregnated sulfated silica as a mesoporous catalyst in the production of biogasoline from used cooking oil via a hydrocracking process

“…This indicates silica contains more physically bound water than SO 4 -SiO 2 and Cr/SO 4 -SiO 2 . The second step, in the range of 200-400°C corresponds to the release of vicinal silanol (bridging silanol) groups in the SiO 2 [45], the mass reduction of SiO 2 , SS 2-600, and Cr-SS 1 as much as 0.98%, 0.54%, and 0.34%, respectively. In the 400-900°C range, the third step corresponds to releasing geminal silanol groups in the SiO 2 [46].…”