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2 Conversion with SOCs 5
Published in Yun Zheng, Bo Yu, Jianchen Wang, Jiujun Zhang, Carbon Dioxide Reduction through Advanced Conversion and Utilization Technologies, 2019
Yun Zheng, Bo Yu, Jianchen Wang, Jiujun Zhang
In general, water,133 camphene,125–127 and tert-butyl alcohol134,135 are widely used as dispersion media in freeze casting. Among them, water is the most commonly used solvent because it is clean, available, and low cost. The morphology of ice crystals during the freeze casting is determined by the competitive relation between ice nucleation and ice growth.136–140 The morphologies of ice crystals are different under different freezing condition, including needle, columnar, layered, and branched pores. The common ice molecule structure is shown in Figure 10.11a.95 If the freezing temperature gradually decreases, the whole slurry system can be assumed to be in thermal equilibrium. In this case, ice crystals first nucleate on the surface of slurry and then grow downward along the direction of the temperature gradient.
Functional Nano-Bioconjugates for Targeted Cellular Uptake and Specific Nanoparticle–Protein Interactions
Published in Grunwald Peter, Biocatalysis and Nanotechnology, 2017
Sanjay Mathur, Shaista Ilyas, Laura Wortmann, Jasleen Kaur, Isabel Gessner
The Cu(I)-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition of azides and alkynes (CuAAC), which has become increasingly popular to afford 1,2,3-triazoles (Hein et al., 2008), owes its usefulness in part to the ease with which azides and alkynes can be introduced into a molecule and their relative stability under a variety of conditions. In addition, CuAAC reaction can be performed in a variety of solvents such as water, ethanol or tert-butyl alcohol, etc. (Tornøe et al., 2002). Other advantages of CuAAC reaction include mild reaction conditions, high yield and efficiency under physiological conditions, and its chemo- selectivity, which allows labeling of functional biomolecules such as peptides, proteins, nucleic acids, polysaccharides, etc. (Rostovtsev et al., 2002). However, the original Huisgen 1,3- cycloaddition reaction, i.e., the reaction of unactivated azides and alkynes proceeds slowly in the absence of a catalyst and generally requires elevated temperatures and long reaction time and yields a mixture of 1,4- and 1,5-triazoles, rendering this reaction unsuitable for most biomedical applications (Fig. 21.2).
Fuel Production by Supercritical Water
Published in Yatish T. Shah, Water for Energy and Fuel Production, 2014
Some details of the specific examples quoted by Savage [11] as they relate to fuels are worth noting. As an example of C-C bond formation, both phenol and p-cresol can be successfully alkylated with tert-butyl alcohol and 2-propanol at 275°C in the absence of any added acid catalyst to produce sterically hindered phenols [18]. Water in these alkylation reactions serves as both catalyst and reactant. Xu and Antal [21,22] were successful in converting tert-butyl alcohol to isobutylene by dehydration reaction. In the absence of an added acid, hydronium ions formed by the dissociation of water are the primary catalytic agents. The dehydration of other alcohols such as cyclohexanol, 2-methylcyclohexanol, and 2-phenylethanol to form alkenes is also reported [23-25]. Esters can undergo an autocatalytic hydrolysis to form carboxylic acids and alcohols [17,18]. Partial oxidation of methane in SCW at 400°C to form methanol has been explored with both homogeneous free radical reactions [26,27] and heterogeneous catalytic reactions [28]. High selectivities for oxygenates, but very low methane conversions, have been obtained. More research to synthesize fuel components or fuel additives in SCW continues to be pursued.
Heterogeneous Catalytic Ozonation for Water Treatment: Preparation and Application of Catalyst
Published in Ozone: Science & Engineering, 2023
Zekun Yang, Haitao Yang, Yong Liu, Chaoquan Hu, Hailong Jing, Hongtao Li
HO‧ quenching agent is also often used to investigate the mechanism of catalytic ozonation. Tert-butyl alcohol (TBA), as a common free radical quenching agent, is widely used in the capture of HO‧ in ozonization reaction systems due to the very rapid reaction between TBA and HO‧ (reaction rate constant is 6.0 × 108/(mol·s)). However, it reacts very slowly with O3 (the reaction rate constant is only 3.0 × 10−3/(mol·s). At the same time, according to the physical and chemical characteristics of TBA, TBA is difficult to be adsorbed by the catalyst. Alver et al. added TBA to the reaction system for the catalytic ozonation of natural organic matter (NOM) with iron pumice coating (Alper et al., 2018). The results showed that the addition of TBA significantly inhibits the removal of NOM and concluded that HO‧ is the main oxidizing species in the established system. Bing et al. degraded p-chlorobenzoic acid (p-CBA) by catalytic ozonation using MCM-41 molecular sieve loaded with CE, and all p-CBA can be removed after 7 min reaction. After 10 mg·L−1 TB is added into the system, the p-CBA removal rate is only 83.6% after 10 min reaction. Therefore, the degradation of p-CBA by the established system follows the HO‧ oxidation path (Bing et al. 2013).