Synthesis of alcohols from CO and H<Subscript>2</Subscript> on iron catalysts containing carbon fiber

It was found that alcohols can be synthesized from CO and H₂ at 3 MPa and 280–300°C in the presence of Fe catalysts containing an activated fibrous carbon material (AFCM) as a support. It was established that 20% Fe/AFCM catalysts possess an extremely high specific activity in the conversion of carbon monoxide (∼1 × 10⁻⁴ mol CO (mol Fe)⁻¹ s⁻¹), which is higher than the activity of traditional bulk iron catalysts by almost an order of magnitude. The values of CO conversion and selectivity for alcohols obtained for these catalysts are close to the parameters of industrial processes (Synol process, Oxyl process, and synthesis according to Bashkirov); however, they are obtained under milder conditions in a single run rather than with the use of a recycle. The Fe/AFCM catalysts make it possible to obtain monohydric alcohols in yields to ∼50 g/m³ (to a 50% concentration in synthesis water) upon the almost complete conversion of CO. In this case, the fraction of C₂-C₄ alcohols was as high as 55–60%.     

The Use of Biochar as Filler in Polyurea Lubricants

Chemistry and Technology of Fuels and Oils - The possibility of using biochar of plant origin as filler in polyurea plastic greases was studied, and its effect on their performance was...     

Enhanced Low Temperature NO x Reduction Performance Over Bimetallic Pt/Rh–BaO Lean NO x Trap Catalysts

The overall NSR operation was tested over a bimetallic Pt/Rh–BaO lean NO _x trap (LNT) catalyst in the range of 473–673 K with simulated diesel exhausts and compared to monometallic 1 wt% Pt/BaO/γ-Al₂O₃ and 0.5 wt% Rh/BaO/γ-Al₂O₃ samples. The results showed the beneficial effect of the simultaneous presence of 0.5 wt% Pt and 0.25 wt% Rh on the catalytic performance under lean-burn conditions at low temperatures. It was observed that both Pt/BaO/γ-Al₂O₃ and Rh/BaO/γ-Al₂O₃, which both were mildly aged, have limited NO _x reduction capacity at 473 K. However, combining Pt and Rh in the NO _x storage catalyst assisted the NO _x reduction process to occur at lower temperatures (473 K). One possible reason could be that the combined Pt and Rh sample was more resistant to aging. In addition, the NO₂-TPD data showed that the presence of Rh into the Pt/BaO/γ-Al₂O₃ system has a considerable effect on the spill-over process of NO _x , accelerating the release of NO _x at lower temperatures. These results were in a good agreement with the observed higher rate of oxygen release of the bimetallic Pt/Rh catalyst, leaving a significant number of noble metal sites available for adsorption at lower temperatures than that of the monometallic Pt sample. The superior NSR performance of the bimetallic Pt/Rh/BaO/γ-Al₂O₃ catalyst under lean-burn conditions suggested the existence of synergetic promotion effect between the Pt and Rh components, increasing the NO _x reduction efficiency in comparison with that of the monometallic Pt and Rh–BaO LNT catalysts.     

Fischer-Tropsch synthesis in presence of composite materials containing iron and cobalt nanoparticles

Fischer-Tropsch synthesis in a static catalyst bed and in a three-phase system in the presence of composite materials containing iron and cobalt particles in the nano-size range 30-60 nm is investigated. It is shown that in both process implementation methods the yield and selectivity of liquid hydrocarbon formation increase with iron content in the composite material. In this case, the catalysts exhibit higher activity in the static bed and greater selectivity in the three-phase system. In the static bed of the most active catalyst containing 44.4 % iron and 33.3 % cobalt, the yield of C₅₊ hydrocarbons was 103 g/m³.     

A heuristic algorithm for lightpath scheduling in next-generation WDM optical networks

We study the routing and wavelength assignment (RWA) problem of scheduled lightpath demands (SLDs) in all-optical wavelength division multiplexing networks with no wavelength conversion capability. We consider the deterministic lightpath scheduling problem in which the whole set of lightpath demands is completely known in advance. The objective is to maximize the number of established lightpaths for a given number of wavelengths. Since this problem has been shown to be NP complete, various heuristic algorithms have been developed to solve it suboptimally. In this paper, we propose a novel heuristic RWA algorithm for SLDs based on the bee colony optimization (BCO) metaheuristic. BCO is a newborn swarm intelligence metaheuristic approach recently proposed to solve complex combinatorial optimization problems. We compare the efficiency of the proposed algorithm with three simple greedy algorithms for the same problem. Numerical results obtained by numerous simulations performed on the widely used realistic European Optical Network topology indicate that the proposed algorithm produces better-quality solutions compared to those obtained by greedy algorithms. In addition, we compare the results of the BCO–RWA–SLD algorithm with four other heuristic/metaheuristic algorithms proposed in literature to solve the RWA problem in the case of permanent (static) traffic demands.