Band 34, Heft 1

Recently, hydrogen is utilized by numerous chemical industries as an alternate over non-renewable fuels, and surely it will be considered as an important fuel in the near future. This paper reports a review of various reforming technologies for hydrogen production from butanol produced by fermentation of feedstocks like wheat, sugar beets, sugar cane, etc. with a number of aspects involving selection of an appropriate catalyst to suppress undesirable products as many reforming reactions are dependent on the catalyst properties to enhance the formation of significant fuels which may fulfill the future energy needs. An overview of butanol reforming processes with experimental and theoretical studies in order to grasp possibilities and restrictions of these processes is not comprehensively presented yet. In this paper, an assessment of published articles in brief related to essential parameters to carry out a pertinent research in the future is presented for the advancement of fuel processing technologies.

Oil shale is one of the largest, relatively undeveloped natural fossil fuel resources in the world and so an important potential source of energy. The organic matter of oil shale is present as a complex combination of carbon, hydrogen, sulfur and oxygen named kerogen. Pyrolysis-gas chromatography-mass spectroscopy affords the opportunity to chemically characterize the main structural skeleton in this kerogen and is a favorable method to study the structural characteristics of kerogen at a molecular level. The thermal degradation of oil shale kerogen is a complex chemical process, accompanied by the wide variety of products obtained, which poses difficulties in the determination of the kinetics and mechanism of pyrolysis. Understanding the kinetics of kerogen decomposition to oil is critical to design a viable retorting process. Comprehensive kinetic data are also essential for accurate mathematical modeling of various oil shale processes. Classic graphical methods cannot unambiguously measure and estimate kinetic parameters due to the mathematical complexity. Advanced isoconversion methods would be appropriate for the calculation of the distribution of activation energies for multiple reactions involved in the decomposition of complex material such as kerogen to products. The range of variability in the principal activation energy is from about 200 to 242 kJ mol −1 , with most samples being in the middle half of that range, while the range of frequency factors most likely in the 10 12 –10 16 s −1 range, with most values within the middle half of that range. The review presents the complexity of the oil shale pyrolysis mechanism and pyrolysis kinetics along with the challenges in experimental procedures and modeling of oil shale pyrolysis kinetics.

The statistical information on the share of hydrogen sector-wise consumption indicates that 95% of the total consumption is utilized in ammonia synthesis, petroleum refining processes and methanol production. We discuss how hydrogen is used in these processes and in several smaller-scale manufacturing industries. We also present the trend of hydrogen used as fuel, and as an energy carrier in fuel cells for generating electricity, powering hydrogen vehicles, as well as in aerospace applications. Natural gas caters for approximately half of the total hydrogen production resources. Therefore, the scope is emphasized on relatively recent developments in research activities related to the conventional catalytic hydrocarbon processing technologies for the production of hydrogen derived from natural gas (methane), which are steam methane reforming, partial oxidation of methane and autothermal reforming. Hydrocarbon decomposition is included due to its potential to be industrialized in the future, and its benefits of producing clean hydrogen without emissions of greenhouse gases and generating carbon nanofibers or nanotubes as by-products that have the potential in various emerging applications. Attention is given to the efforts toward achieving hydrocarbon conversion improvements, energy savings through thermally efficient operation and reduced operational costs through minimization or elimination of coke formation in the catalytic processes.

The main aim of this article is to provide a state-of-the-art review of the experimental studies on vacuum membrane distillation (VMD) process. An introduction to the history of VMD is carried out along with the other membrane distillation configurations. Recent developments in process, characterization of membrane, module design, transport phenomena, and effect of operating parameters on permeate flux are discussed for VMD in detail. Several heat and mass transfer correlations obtained by various researchers for different VMD modules have been discussed. The impact of membrane fouling with its control in VMD is discussed in detail. In this paper, temperature polarization coefficient and concentration polarization coefficient are elaborated in detail. Integration of VMD with other membrane separation processes/industrial processes have been explained to improve the performance of the system and make it more energy efficient. A critical evaluation of the VMD literature is incorporated throughout this review.

Colored effluents containing dyes from various industries pollute the environment and pose problems in municipal wastewater treatment systems. Industrial effluents consist of a mixture of dyes and require study of the simultaneous removal of dyes. Simultaneous quantification of dyes in the solution is a common problem while using a spectrophotometric method due to overlapping of their absorption spectra. Derivative spectroscopy and chemometric methods in spectrophotometric analysis facilitate simultaneous quantification of dyes. Adsorption is a widely used treatment method for the removal of a mixture of recalcitrant dyes in industrial wastewaters. Confirming the assertion, this paper presents a state-of-the-art review on methods used for simultaneous quantification of dyes and the effects of various parameters on their adsorptive removal. This paper also reviews the adsorption equilibrium, modeling, mechanisms of dyes adsorption, and adsorbent regeneration techniques in multicomponent dye systems. It has been observed that chemometric techniques provide accuracy, repeatability, and high speed in processing and helps in better operability in real wastewater treatment plants. The conclusions include the need for the development of thermodynamic models that can predict simultaneous physisorption and chemisorption exhibited by different dyes and to develop isotherm models that can describe chemisorption of a mixture of dyes. The paper delves into inadequately researched gray areas of adsorption of a mixture of dyes which require the development of modified adsorption methods that serves process intensification for complete degradation/mineralization.