No abstract

The emission of carbon dioxide (CO 2 ) and other pollutants which result from burning fossil fuels has been identified as the major contributor to global warming and climate change. However, for the immediate term, over the next 10 -20 years at least, the world will continue to rely on fossil fuels as the source of primary energy. The challenge for the fossil fuel industry is to find cost-effective solutions that will reduce the release of CO 2 and other pollutants into the atmosphere.The focus of this paper is on the ability to treat the exhaust gas from fossil fuel power plants in order to capture and store the CO 2 and remove other pollutants such as SO x and NO x which are released in the atmosphere.In summary, capture/separation costs represent the largest financial impediment for these types of plants. Hence, efficient, cost-effective capture/separation technologies will need to be developed to allow their large-scale use.

Purpose: At thermal power plants the fly ash (FA) is stored either through dry or wet disposal systems. These storage practices result in different features for fly ashes, such as their interaction with alkalis and hence the potential of zeolite synthesis will be different. With the aim to demonstrate this, it was conducted some investigations to study the physical, chemical, morphological and mineralogical characteristics of the fly ash residues, then were used to synthesis zeolites by a double stage fusion-hydrothermal method. Design/methodology/approach: The raw and converted fly ash samples were characterized with respect to their composition, crystallinity and morphology, by SEM and XRD analysis. The effects of environment conditions and process parameters on the zeolitization process were studied and analysed. Findings: The analysis of these residues showed that dry ash attains a high cation exchange capacity (CEC) and SiO2 /Al2O3 ratios, which is in agreement to the formation of fly ash zeolites as compared to its counterpart. The experimental results indicate that the fusion temperature does not influence on the synthesis mechanism in range of 500-800 (°C) having only an effect of acceleration. The increasing of alkaline activator/fly ash ratio enhances the zeolitization degree. Research limitations/implications: The scientific basis for the issues on the zeolitization characteristics of fly ash and its use to manufacture porous materials calls yet for further elucidation and development. Practical implications: This study helps to establish the superiority of dry ash over wet ash for synthesizing porous materials and their enhanced quantity and quality. Originality/value: A new route for the fly ash use is demonstrated and this can become an unavoidable task for porous material manufacturing, a viable way to manage this industrial waste and to protect the environment.

This paper presnts biomass as a renewable energy source and defines the resources as well as the ways through biomass energy is converted into fuels, the technologies used for extracting the energy from biomass as well as the advantages and disadvantages that appear by using of biomass as a energy source. In addition,it is known hydrogen is an important alternative energy vector and a bridge to a sustainable way fot the energy future. Hydrogen is an energy carrier and can be obtained by different production technologies from a large variety of primary energy sources. At present, many researches are focused on getting energy from biomass, a sustainable and non-polluting way to replace fossil fuels, because the biomass can be considered as the best option with high potential, which meets energy requirements and could insure fuel supply in the future. Biomass and residual biomass can be used to produce hydrogen rich gas sustainably. Biomass pyrolysis and gasification offers an efficiency and economical route for the renewable hydrogen production and this is also discussed in the paper.

By loading Cr and Zn on 13X zeolite, efficient nanocatalysts were prepared; they were characterized by different techniques and used for corn cobs pyrolysis to produce bio-oil. The corn cobs biomass (CCB) was washed with sulfuric acid 0.1 M, and the characteristics of the pretreated biomass (PTCCB) were analyzed. Pyrolysis was performed at different catalyst-to-biomass ratios (C/B), and the composition of the obtained bio-oil was determined. The results showed that the crystallinity of the nanocatalysts was slightly lower than that of the pattern 13X zeolite. The surface observation of the nanocatalysts showed the presence of pores and particles, which are quite evenly dispersed on the surface, and no difference was observed in the morphology of the Zn/13X zeolite and Cr /13X zeolite nanocatalysts. In comparison to 13X zeolite, the morphological changes, metal dispersion, and surface area decrease of both Zn/13X and Cr/13X zeolite nanocatalysts could be observed. Pyrolysis tests demonstrated that the use of Zn/13X zeolite and Cr/13X zeolite nanocatalysts could be very profitable to obtain a high conversion to hydrocarbons of the compounds containing oxygen, and consequently, the quality of the bio-oil was improved.