LHHW/RSM reaction rate modeling for Co-Mn/SiO2 nanocatalyst in Fishcher-Tropsch synthesis.

This study aims to assess the kinetics of Fischer-Tropsch (FT) reaction over the cobalt-manganese nanoparticles supported by silica oxide. Nanoparticles were synthesized by the thermal decomposition method using "[Co(NH3)4CO3]MnO4" complex and characterized by XRD, TEM, and BET techniques. The kinetics of the process were evaluated using a combination of Langmuir-Hinshelwood-Hougen-Watson (LHHW) and response surface methodology. Correlation factors of 0.9902 and 0.962 were obtained for the response surface method (RSM) and LHHW, respectively. The two methods were in good agreement, and the results showed that the rate-determining step was the reaction of the adsorbed methylene with the adsorbed hydrogen atom, and only carbon monoxide molecules were the most active species on the catalyst surface. A temperature of 502.53 K and a CO partial pressure of 2.76 bar are proposed as the optimal conditions by RSM analysis. The activation energy of CO consumption reaction was estimated to be 61.06 kJ/mol.

Investigation of used cooking oil on the formation of FOG deposits in sewer line clogging.

Fat, oil, and grease (FOG) deposits, resulting from saponification reaction, have been identified as the primary source of blockage of sewer pipes. This mainly emanates from the adhesion of these deposits on pipe walls, culminating in the sanitary sewer overflows (SSOs). This undesired phenomenon poses several challenges for municipalities, including environmental issues, health-related hazards, and an increase in incurred costs. Unlike the previous literature, the present study, for the first time, attempts to characterize the effect of used cooking oils (a mixture of different oils) as a perceived crux, triggering the genesis of deposits. The experimental results revealed that there exists a host of physical and chemical disparities between fresh oil calcium soaps (FOCSs) and used oil calcium soaps (UOCSs). Notably, when mixed with water, FOCSs produced non-miscible layers, whereas a homogenous, sticky, and viscous solution observed for UOCSs. Fourier transform infrared (FTIR) analysis casts light on the fact that the heating process would greatly influence the oil chemical structure and its resultant calcium soaps. In comparison with calcium chloride, as time elapsed, the optical microscope images illustrated that the calcium sulfate clots formation proceeded at an accelerated rate, delivering particles with larger sizes. Viscosity and adhesion are two prominent distinctions between soaps. In sharp contrast to soap produced from oil with a higher palmitic acid content, it was discerned that the oil containing less palmitic acid generates UOCSs with higher viscosity and adhesion than FOCSs. It can therefore be inferred that the distinct chemical structures driven by high temperature during the cooking process produce soaps with different characteristics as compared with fresh oil. This phenomenon would have a profound impact on the formation of the deposits in sewer lines.

Maximizing HBr/Br2 in the flue gas and prevention of secondary pollution during the oxy-combustion of brominated waste electrical and electronic equipment part 1- thermodynamic considerations.

Organobromine compounds comprise between 3 and 8% by weight of WEEE and mainly converted to HBr and Br2 in the incinerator. However, these compounds, during the cooling of the flue gases, can form the PBDD/Fs in the post-combustion area of the furnace. Due to the many benefits of Oxy-combustion process, our group has developed a fluidised bed incinerator for burning the WEEE and plan to maximise HBr/Br2 in the flue gas. Experimental results presented in the recent papers show that the combustion of the WEEE particles attains quickly to thermodynamic equilibrium. Thermodynamic modelling can, therefore, predict the concentration of brominated pollutants, particularly HBr, Br2, HgBr2, and Br˙ in the flue gas. In this paper, the effect of various parameters for increasing the HBr/Br2 ratio in the flue gas has been investigated. The model shows that the addition of very small amounts of hydrogen in the post-combustion area can convert Br2 and Br˙ into HBr.