Thermal manganese oxidation

A variety of methods have been applied to the measurement of EC and OC in aerosol samples with the thermal, thermal optical reflectance (TOR), and thermal manganese oxidation (TMO) methods being the most popular. Understanding the operational principles of these methods is often necessary for the interpretation of reported EC and OC data. 

A thermally stable, pure todorokite has been synthesized by autoclaving a layered stmctured manganese oxide, initially generated from the reaction of MnO and Mn " under alkaline conditions. The synthetic manganese oxide molecular sieve (11) was shown to have a tunnel size, ie, diameter of 690 pm. This material was thermally stable to 500°C just as natural todorokite is (68). 

The reduction of manganese oxides by aluminum has been used for the production of manganese metal. The process is also a classic example to illustrate thermal energy management in a typical aluminothermic reduction process. 

Preliminary electrochemical tests of materials obtained have been performed in two types of cells. Primary discharge measurements have been executed in standard 2325 coin-type cells (23 mm diameter and 2.5 mm height) with an electrolyte based on propylene carbonate - dimethoxyethane solution of LiC104. Cathode materials have been prepared from thermally treated amorphous manganese oxide in question (0.70 0.02g, 85wt%.) mixed with a conductive additive (10 % wt.) and a binder (5wt%). Lithium anodes of 0.45 mm thickness have been of slightly excess mass if compared to the stoichiometric amount, so as to ensure maximal possible capacity of a cell and full consumption of the cathode material. 

Promising results have also been obtained in cycling ability studies performed in model coin-type cells with this same amorphous cathode material. Moreover, it has been found that either thermally treated or even initial amorphous manganese oxide exhibit satisfactory results. Cyclic voltammetric studies have been carried out with the LP-30 electrolyte (Merck). Cathode materials have been prepared from amorphous manganese oxide in question (80wt%) mixed with a conductive additive (10wt%) and a... 

In the preparation of microporous manganese oxide materials different chemical properties were observed for the microwave and thermal preparations. In the conversion of ethylbenzene to styrene the activity and selectivity of the materials was different [26]. 

Still another explanation is that the thermal decomposition of MnC03 to MnO and the later slaking of MnO forms an alkaline environment. This process has occurred to some extent in the ore deposits however, it does not explain the fact that many of the native lead-pyrochroite veins occur in hausmannite ores, where the manganese oxides are altered or completely leached away close to the vein. 

The residue cannot be identified as one of the manganese oxides and used in calculating manganese content by the usual methods such attempts gave exaggerated results. In fact, the residue is a macromolecular compound resulting from the thermal transformation of the polychelate it is not transformed any farther at high temperatures (about 1000°C). 

A large number of unsymmetrical ketones have been prepared by the thermal decarboxylation method however, the yields are not recorded. In general, by using a large excess of the short-chain acid (which minimizes formation of the long-chain symmetrical ketone) over thoria at 400°, yields of about 50% are obtained. ° Methyl benzyl ketone and other alkyl aryl ketones have been synthesized in this manner (65%). The use of manganese oxide catalyst at 400° gives about the same results. ... 

Several methods have been used to produce different types of OL-1, OMS-1, and OMS-2 materials. The materials that are produced by various methods lead to vastly different materials, that have unique chemical and physical properties. Some of the properties that can be controlled are particle size, color, morphology, average manganese oxidation state, thermal stability, ion-exchange capacity, electrical conductivity, magnetic properties, crystallinity, defect density, desorption of oxygen, and catalytic properties. Table IV summarizes 16 different classes of OMS-1, OMS-2, OL-1, and amorphous manganese oxide (AMO) materials that we have prepared. These materials are separated into different classes because they show different crystalline, chemical and physical properties. For the case of OMS-1 these materials... 

Tian[240] prepared hexagonal and cubic phases of manganese oxide mesoporous structures by means of the oxidation of Mn(OH)2. The hexagonal materials form thick walls (1.7 nm) and exhibit exceptional thermal stability (1000 °C). The walls of the mesopores are composed of microcrystallites of dense phases of Mn203 and Mn304, with Mn06 octahedra as the primary building blocks. 

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