Chemistry of coal-related microparticles

A new type of electrodynamic balance was designed, constructed and applied to the study of the chemistry of macerals and the chemical reaction between CaO sorbent particles and SO[sub 2]. The single-particle device was coupled to a Raman spectrometer. With this balance a single electrically charged microparticle is suspended in visible and infrared laser beams by means of superposed ac and dc electrical fields. The apparatus was designed to permit gas flow through the chamber so that gas-solid and gas-liquid chemical reactions can be carried out. A visible laser beam was used to illuminate the particle for Raman and fluorescence measurements, and an infrared laser beam was used to heat the particle. An overview of the experimental system is presented in Figure 1. The levitated particles were heated from two sides using a CO[sub 2] laser operating at the infrared wavelength of 10.6 [mu]m. The optical system used to direct the heating laser beam to the target is shown in Figure 2. Infrared detectors indicated in Figure 1 were used to measure the particle temperature by two-color pyrometery. A new technique was explored to independently determine the particle temperature; the method involves measuring the ratio of the intensities of Stokes and anti-Stokes Raman scattering signals. Although the method is not accurate near room temperature because of the weak and-Stokes signal at low temperatures, the method appears promising for high temperature measurement, and complements the pyrometry method. Optical pyrometry is quite suitable for black body emitters, but for the metal oxides of interest here, optical pyrometry was found to be less satisfactory than an alternate method

Chemistry of coal-related microparticles

The objective of this research is to develop and apply novel single microparticle techniques to perform simultaneously thermogravimetric analysis and Raman/fluorescence spectroscopies on microparticles of coal (macerals) and sorbents (CaO) used for coal desulfurization. The combination electrodynamic balance/spectrometer system is being used to chemically characterize macerals from different ranks of coal and to explore the chemistry and chemical reaction rates associated with processes involving such microparticles. Rate processes will be examined at elevated temperatures by heating the particles electromagnetically, and significant part of the research involves the design, construction and utilization of a microparticle heating system

Microwave-assisted thermochemical and primary hydrolytic conversions of lignocellulosic resources: a review

peer reviewedFaced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as promising renewable alternatives. Particularly, the conversion of lignocellulosic materials has nowadays opened new vistas for the production of energy, biofuels and chemicals. In this literature review, microwave technology is described as an original heating source either for the thermochemical conversions (at temperatures up to 400°C) of lignocellulose into biofuels or the pretreatment (below 400°C) and further hydrolysis of lignocellulose into bioethanol and other valuable chemicals. Advantages of microwave approaches include a commonly observed acceleration in reaction rate and improved selectivities and yields