Catalytic hydrothermal processing

Biller, R, Riley, R., Ross, A. B. Catalytic hydrothermal processing of microalgae decomposition and upgrading of hpids. Bioresource Technol 2011,102,4841-4848. 

In petrochemical and oil refining operations, the zeolite is primarily responsible for the catalyst s activity, selectivity and stability (catalytic, thermal and hydrothermal). The fluid catalytic cracking process (FCC) is the most widely used of the oil refining process and is characterized by the use of a finely divided catalyst, which is moved through the processing unit. The catalyst particles are of such a size (about 70 pm) that when aerated with air or hydrocarbon vapor, the catalyst behaves like a liquid and can be moved easily through pipes. 

Vogel, F., Hildebrand, F. (2002) Catalytic hydrothermal gasification of woody biomass at high feed concentrations. Paper 123, 4th International Symposium On High Pressure Process Technology and Chemical Engineering, EFCE, Venice Italy. 

Park J-H, Park HJ, Baik JH et al (2006) Hydrothermal stability of CuZSM5 catalyst in reducing NO by NH3 for the urea selective catalytic reduction process. Journal of Catalysis 240 47-57... 

The production of nanostructured carbon materials by hydrothermal processes from natural precursors is one of the most attractive subjects in material science today. Carbon materials prepared from hydrothermal process are currently being used in various fields of research including environmental, electrical, chemical, and biomedical fields. In environmental application, carbon is mainly used as a sorbent material for the removal of heavy metal ions (CrO/, Pb +, and Cd +) from water and wastewater [116,117]. Carbon nanocoils prepared from saccharides (sucrose, glucose, and starch) with a support of Pt/Ru nanoparticles exhibit a high catalytic activity for the electro-oxidation of methanol in an acid medium [150]. Similarly, electro-oxidation of ethanol and methanol was carried out with electro catalysts, such as Pd/CHC (coin-like hollow carbon), Pt/ HCS (hard carbon spherules), and Pt/Pd/CMS (carbon microspheres) in acidic and alkaline media... 

Several approaches have been used to tackle the problem of the wastewater byproduct. For example in the case of microalgae HTL, PNNL applied catalytic hydrothermal gasification (CHG) effectively for HTL process water clean-up and fuel gas production... 

Cherad, R., et al., 2015. Hydrogen production from the catalytic hydrothermal gasification of process water from microalgae hquefaction. Fuel 166, 24—28. 

The major drawback of traditional perovskites is low in surface area. As mentioned in Section 2, there are various methods to fabricate hrgh-surface-area perovskites. For example, via a novel strategy of citric acid complexing coupled with a hydrothermal process, high-surface-area (16-33 m /g) nanosized Lai Sr MOs (M = Co, Mn, Fe x = 0, 0.4) and LaoeSro M ogFeo 1O3 (M = Co, Mn) catalysts have been generated by our group [30-32,274]. All of these nanocatalysts show excellent catalytic performance for the complete oxidation of typical VOCs (e.g., toluene and ethyl acetate). Under the reactions of... 

Titanium containing hexagonal mesoporous materials were synthesized by the modified hydrothermal synthesis method. The synthesized Ti-MCM-41 has hi y ordered hexa rud structure. Ti-MCM-41 was transformed into TS-l/MCM-41 by using the dry gel conversion process. For the synthesis of Ti-MCM-41 with TS-1(TS-1/MCM-41) structure TPAOH was used as the template. The synthesized TS-l/MCM-41 has hexagonal mesopores when the DGC process was carried out for less than 3 6 h. The catalytic activity of synthesized TS-l/MCM-41 catalysts was measured by the epoxidation of 1-hexene and cyclohexene. For the comparison of the catalytic activity, TS-1 and Ti-MCM-41 samples were also applied to the epoxidation reaction under the same reaction conditions. Both the conversion of olefins and selectivity to epoxide over TS-l/MCM-41 are found hi er flian those of other catalysts. 

Zeolites are crystalline aluminosilicates with a regular pore structure. These materials have been used in major catalytic processes for a number of years. The application using the largest quantities of zeolites is FCC [102]. The zeolites with significant cracking activity are dealuminated Y zeolites that exhibit greatly increased hydrothermal stability, and are accordingly called ultrastable Y zeolites (USY), ZSM-5 (alternatively known as MFI), mordenite, offretite, and erionite [103]. 

In 2009, Onda et al. studied the catalytic activity of sulfonated activated carbon prepared from active carbon and concentrated sulfuric acid [47]. The hydrolysis was performed under hydrothermal conditions at 423 K in a steel autoclave lined with Teflon. After 24 h of reaction, sulfonated carbon afforded high yield of glucose (40 C-%, i.e., based on the total weight consumption of carbon) and nearly no SO4 elution was observed which clearly indicated that the process was heterogeneously catalyzed. As observed above, under hydrothermal conditions, the glucose yield... 

New applications of zeolite adsorption developed recently for separation and purification processes are reviewed. Major commercial processes are discussed in areas of hydrocarbon separation, drying gases and liquids, separation and purification of industrial streams, pollution control, and nonregenerative applications. Special emphasis is placed on important commercial processes and potentially important applications. Important properties of zeolite adsorbents for these applications are adsorption capacity and selectivity, adsorption and desorption rate, physical strength and attrition resistance, low catalytic activity, thermal-hydrothermal and chemical stabilityy and particle size and shape. Apparent bulk density is important because it is related to adsorptive capacity per unit volume and to the rate of adsorption-desorption. However, more important factors controlling the raJtes are crystal size and macropore size distribution. 

It is well known that the elements in framework of zeolite molecular sieves greatly influence the properties and behaviors of these materials [1-3], The introduction of heteroatoms into the framework has become one of most active fields in study of zeolites. The investigations were mostly focused on the methods to introduce heteroatoms into the framework (for examples, hydrothermal synthesis and post-synthesis), the mechanisms for incorporations, the effect of heteroatoms on the acid-base properties and the catalytic features of modified samples [1-10]. Relatively less attention was paid to the effect of treatment process on the porous properties of samples although the incorporation of heteroatoms, especially by the so-called post-synthesis, frequently changes the distribution of pore size. Recently, we incorporated Al, Ga and B atoms into zeolites (3 by the post-synthesis in an alkaline medium named alumination, galliation and boronation, respectively. It was found that different trivalent elements inserted into the [3 framework at quite different level. The heteroatoms with unsuitable atom size and poor stability in framework were less introduced, leading to that a considerable amount of framework silicon were dissolved under the action of base and the mesopores in zeolite crystal were developed. As a typical case, the boronation of zeolites (3 and the accompanied formation of mesopores are reported in the present paper. 

In our previous paper we have reported that silica MCM-41 exhibits a large amount of reversible adsorption, high thermal and hydrothermal stabilities, and little catalytic acidity and is an excellent adsorbent in PSA process for recovery of 2-propanol and toluene vapors [1]. Here we present the results of PSA of butanone on silica MCM-41 and discuss the effect of pretreatment temperatures on adsorption properties of MCM-41. 

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