Effect of operating conditions and potassium content on Fischer-Tropsch liquid products produced by potassium-promoted iron catalysts

The dependencies of Fischer-Tropsch synthesis liquid hydrocarbon product distribution on operating pressure and temperature have been studied over three potassium-promoted iron catalysts with increasing potassium molar content. The study followed an experimental planning and the results were analyzed based on surface response methodology. The effects of different operating conditions and potassium contents on the liquid product distribution were compared based on number average carbon number and dispersion. Results showed that high pressures （25 to 30 arm） favored the production of waxes that could be converted into liquid fuels through hydrocracking, while greater direct selectivity towards diesel was favored by low pressure （20 arm） using catalysts with low potassium to iron molar ratios. The liquid product distribution produced using an iron catalyst with high potassium content presented higher number-average number of carbons when compared to the distribution obtained using an iron catalyst with low potassium content.

Physicochemical Properties of Rhamnolipid Biosurfactant from <i>Pseudomonas aeruginosa</i>PA1 to Applications in Microemulsions

Interfacial properties rhamnolipids from an extract produced by a strain of Pseudomonas aeruginosa were analyzed in this study. The extract of rhamnolipid was characterized by surface tension in different conditions;interfacial tension with different hydrocarbons;critical micelle concentration under different pH and temperatures;particle size and emulsification capacity using laser light profiling. It was observed that the rhamnolipids extract are sensitive to variations in pH, thermostable and function as good emulsificant for emulsification of methyl methacrylate. The emulsion stability order in function of the oil phase was methyl methacrylate > emulsions of castor oil > emulsion n-heptane > emulsion toluene > emulsion hexadecane > octane emulsion. The data presented show that rhamnolipid extracts may be used to formulate stable emulsions of methyl methacrylate. This process can be used to do nano/microsphere of polymethyl methacrylate.

Compositional engineering of HKUST-1/sulfidized NiMn-LDH on functionalized MWCNTs as remarkable bifunctional electrocatalysts for water splitting

Water-splitting reactions such as the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)typically require expensive noble metal-based electrocatalysts.This has motivated researchers to develop novel,cost-effective electrocatalytic systems.In this study,a new multicomponent nanocomposite was assembled by combining functionalized multiwalled carbon nanotubes,a Cu-based metal–organic framework(MOF)(HKUST-1 or HK),and a sulfidized NiMn-layered double hydroxide(NiMn-S).The resulting nanocomposite,abbreviated as MW/HK/NiMn-S,features a unique architecture,high porosity,numerous electroactive Cu/Ni/Mn sites,fast charge transfer,excellent structural stability,and conductivity.At a current density of 10 mA cm-2,this dual-function electrocatalyst shows remarkable performance,with ultralow overpotential values of 163 mV(OER)or 73 mV(HER),as well as low Tafel slopes(57 and 75 mV dec-1,respectively).Additionally,its high turnover frequency values(4.43 s-1 for OER;3.96 s-1 for HER)are significantly superior to those of standard noble metal-based Pt/C and IrO2 systems.The synergistic effect of the nanocomposite's different components is responsible for its enhanced electrocatalytic performance.A density functional theory study revealed that the multi-interface and multicomponent heterostructure contribute to increased electrical conductivity and decreased energy barrier,resulting in superior electrocatalytic HER/OER activity.This study presents a novel vision for designing advanced electrocatalysts with superior performance in water splitting.Various composites have been utilized in water-splitting applications.This study investigates the use of the MW/HK/NiMn-S electrocatalyst for water splitting for the first time to indicate the synergistic effect between carbon-based materials along with layered double hydroxide compounds and porous compounds of MOF.The unique features of each component in this composite can be an interesting topic in the field of water splitting.

Methane Direct Conversion on Mo/ZSM-5 Catalysts Modified by Pd and Ru

The effect of addition of Ru and Pd to Mo/HZSM-5 catalysts used in the dehydroaromatization of methane was investigated. Catalytic tests and temperature-programmed oxidation results showed that Pd-based catalysts were more selective to naphthalene and suffered strong deactivation. The presence of Ru improved the activity and stability, with a decrease in the carbonaceous deposit probably because of a mechanism of protection of the Mo2C surface.

Microalgae Lipid and Biodiesel Production: A Brazilian Challenge

Global increases in atmospheric CO2 and climate change are drawing considerable attention to identify sources of energy with lower environmental impact than those currently in use. Biodiesel production from microalgae lipids can, in the future, occupy a prominent place in energy generation because it represents a sustainable alternative to petroleum-based fuels. Several species of microalgae produce large amounts of lipids per biomass unit. Triacylglycerol is the fatty acid used for biodiesel production and the main source of energy reserves in microalgae. The current literature indicates that nutrient limitations can lead to triacylglycerol accumulation in different species of microalgae. Further efforts in microalgae screening for biodiesel production are needed to discover a native microalgae that will be feasible for biodiesel production in terms of biomass productivity and oil. This revision focuses in the biotechnological potential and viability of biodiesel production from microalgae. Brazil is located in a tropical region with high light rates and adequate average temperatures for the growth of microalgae. The wide availability of bodies of water and land will allow the country to produce renewable energy from microalgae.

Growth of Variable Aspect Ratio ZnO Nanorods by Solochemical Processing

In this work,variable aspect ratio（length divided by diameter） zinc oxide nanorods were synthesized through a simple solochemical method by reacting a Zn2+precursor with sodium hydroxide at low reaction temperatures.The analysis of the X-ray diffraction data indicated that the samples had hexagonal wurtzite structure and nanometric size crystallites.The transmission electron microscopy（TEM） images of the products prepared at60 and 80 ℃ exhibited rod-like architecture,showing that the reaction temperature did not affect the ZnO morphology.The average aspect ratio of the ZnO nanorods decreased from 3.4 to 2.4 when the reaction temperature was raised from 60 to 80 ℃.The samples presented a blue shift in the excitonic absorption compared to ZnO bulk that increased alongside with reaction temperature.In addition,this research investigated the results obtained by varying the concentration of zinc chloride solution.At the same temperature,it could be verified that when the zinc concentration was increased,the diameter of the ZnO nanorods also slightly increased,and much shorter nanorods were achieved,especially in the reactions performed at 50 and 70 ℃.Finally,the growth mechanism of the ZnO nanostructures was proposed based on the results obtained by changing the zinc precursor concentration and reaction temperature.

Gold Supported on Metal Oxides for Carbon Monoxide Oxidation

Au 被装载了(1% wt ) 在不同广告上，氧化物支持(CuO， La2O3， Y2O3， NiO ) 由三个不同方法：两倍受精(暗淡) ，液体阶段减少的免职(LPRD ) ，和 ultrasonication (美国) 。样品被 N2 吸附描述在 ? 196 ??  ??????  ??  ? 洠浡業汬牡 ?  ???? 猠'T 業牣吗？

An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater

An advanced anaerobic biofilter（AF） was introduced for the treatment of coal gasification wastewater（CGW）,and effluent recirculation was adopted to enhance phenol removal and methane production.The results indicated that AF was reliable in treating diluted CGW,while its efficiency and stability were seriously reduced when directly treating raw CGW.However,its performance could be greatly enhanced by effluent recirculation.Under optimal effluent recirculation of 0.5 to the influent,concentrations of chemical oxygen demand（COD） and total phenol in the effluent could reach as low as 234.0 and 14.2 mg/L,respectively.Also,the rate of methane production reached 169.0 m L CH_4/L/day.Though CGW seemed to restrain the growth of anaerobic microorganisms,especially methanogens,the inhibition was temporary and reversible,and anaerobic bacteria presented strong tolerance.The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater（GW）.However,the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication.By analysis using the Haldane model,it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters,but only suitable effluent recirculation could result in high methanogenic activity.

Utilization of Acai Berry Residual Biomass for Extraction of Lignocellulosic Byproducts

According to the National Company of Supplying(CONAB)in 2017 alone,the national production of acai pulp reached 219855 t,equating to 180 million dollar(USD).Almost 85%of the weight of fruit is constituted by residual biomass,even though researches have highlighted important applications for this biomass,most of it is discarded as organic waste.Thus,it is relevant to envisage in-depth studies about how to use these residues,particularly regarding the environmental impact of its target destination.Nanocrystalline cellulose(CNC)and lignin are organic derivatives obtained through the physical-chemical treatment of lignocellulosic biomass.Both are abundant and currently considered as biopolymers because of their structural characteristics and their diverse applications in food and the medical field.This work presents the mass yields achieved and the physical-chemical characteristics of the lignocellulosic derivatives extracted from the fiber of the acai berry.A statistical design was used to define the influence of process variables as temperature,reaction time and fiber size on the yield of these byproducts.A maximum yield close to 64%of type I CNC,with 45%of crystallinity degree was achieved at the minimum condition of temperature and fiber size.Additionally,through rheological analysis,it was possible to predict the nanocrystal aspect ratios,ranging from 71 to 125.The extracted lignin was rich in methoxy groups,p-coumaryl alcohol and p-coumaric acid,and its structural unit’s low state of aggregation can be an indication of low molecular weight,which envisions an appropriate use for this lignin to produce commodity chemicals.