Synthesis and Characterization of Nanocrystalline M-Mg-O and Carbon-Coated MgO Systems

Abstract

Two different approaches to modify the structure and reaction ability of nanocrystalline MgO have been discussed. In the first case, a series of two-component x%MOx–MgO systems (M = Fe, Co and Ni, x = 1–45 wt.%) was synthesized via sol–gel technique. Aqueous solution of inorganic salt precursor was used as a hydrolyzing agent. Samples obtained were characterized by number of physicochemical methods (differential thermal analysis, X-ray diffraction analysis, low-temperature adsorption, etc.). It was shown that presence of inorganic salt in magnesium hydroxide matrix shifts the temperature of decomposition of latter towards lower values. Structural and textural characteristics of MgO-based oxide systems were found to be strongly affected by the presence of additive and their concentration. Formation of joint phase was observed in the case of cobalt oxide only. Second way of MgO modification was represented by creating a controlled carbon coating over its surface via decomposition of C4H10 at 400 °C. The obtained x%C/MgO (x = 1–10 wt.%) samples were shown to possess the improved reaction ability in destruction sorption of CF2Cl2 as well as in catalytic dehydrochlorination of 1-chlorobutane in presence of water vapors.

Sol-Gel Synthesis and Characterization of the Cu-Mg-O System for Chemical Looping Application

“…In the present work, the oxide system Cu-Mg-O containing 15 wt% of CuO was synthesized by the sol-gel method. Recently, the effect of the CuO concentration on the textural properties was studied; the loading of 15 wt% was found to be an optimal value [ 72 ]. The copper salt-precursor was added at the stage of the gel formation.…”

Synthesis of novel WO3/ZrSiO4 catalysts for dehalogenation of halogenated hydrocarbons

“…The most common dehalogenation catalysts are based on mixed metal oxides and a certain amount of platinum group metals. The main active component is ZrO2 and/or TiO2, and others are WO3, V2O5, SnO2 and Pd, Pt or Rh [4][5][6][7]. Although catalysts with noble metals are highly active and enable a complete decomposition of halogenated hydrocarbons [3], efficient CFC-12 treatment systems can only contain oxides.…”

“…Process stages of those routes involve: 1) preparing solutions of chemicals used for catalyst synthesis; 2) preparing precursors for catalysts by adjusting solution pH values or by enabling other chemical reactions in the solutions; 3) filtration of formed precursor precipitates; 4) drying of the precursors or, depending on a route, multiple rinsing, filtration, and drying; 5) calcination in a suitable atmosphere to obtain catalyst in the form of powder; 6) supplementary treatment of the catalyst to form the desired shape (pressing, pelletizing, monolithic honeycombs washcoating and other). Despite obtaining high-performance catalysts, thermo-chemical synthesis routes are complex from a cost-effective point of view: they last from 30 to 50 hours or even up to a few days and require large amounts of complex chemical composition solutions [2,[4][5][6][7][8][9][10]. Hence, it is highly desirable to simplify the catalyst production processes by reducing the number of process stages and in conjunction also achieve a lower environmental impact when compared with the thermo-chemical synthesis routes [11][12][13].…”