Fischer-Tropsch Wax Research Articles

Relating rheological measurements to primary and secondary skin feeling when mineral‐based and Fischer–Tropsch wax‐based cosmetic emulsions and jellies are applied to the skin

Rheology measurements were correlated to skin sensations occurring when cream and petroleum jelly cosmetic products containing different amounts of synthetic Fischer-Tropsch wax were applied to the skin. A panel of 15 people with a background in cosmetic product development were asked to rate skin feelings when a range of petroleum jelly and cream samples are applied to the skin. Primary skin feel, or the spreadability of a cosmetic product, was correlated to the product's flow onset and maximum viscosity as measured by a Anton Paar rheometer, whereas secondary skin feel or the sensation occurring at the end of application when the product was completely rubbed into the skin was correlated to the product's viscosity measured at high shear rates. The cream samples prepared with a petroleum jelly containing 10% and 20% Fischer-Tropsch wax fell within the boundary of good primary skin feeling of cream products. Predominantly, synthetic petroleum jellies were given the best assessments in terms of primary skin feeling and were used with mineral-based petroleum jellies to determine the boundary of good primary skin feeling for petroleum jelly products. The further away a product falls from this rheological boundary the poorer the skin feeling assessment appears to be by the panel. Products containing Fischer-Tropsch waxes were given the best assessment by the panel for secondary skin feeling. Comments from the panel include that these products feel silky and light on the skin. The higher the Fischer-Tropsch wax content, the lower viscosity was at high shear rate (ϒ=500s(-1) ) and the higher the assessment by the panel. Rheological measurements can be used to objectively determine skin sensation when products are applied to the skin; this may shorten research and development times. A rheology boundary of certain product viscosity and shear stress applied is associated with good primary skin feeling for lotions, creams and petroleum jellies. Lower product viscosity at high shear rate seems to be associated with better secondary skin feeling. Products with higher Fischer-Tropsch wax content appear to be rated higher in terms of secondary skin feeling.

Hydrocracking and Hydroisomerization of n-Hexadecane, n-Octacosane and Fischer–Tropsch Wax Over a Pt/SiO2–Al2O3 Catalyst

The hydroisomerization and hydrocracking of long chain n-paraffins and a Fischer–Tropsch wax produced with a cobalt catalyst were accomplished over a Pt–amorphous silica–alumina catalyst. The relative conversion of the n-hexadecane and n-octacosane mixed feed greatly favored the higher carbon number compound even though the conversions of the pure hydrocarbons were the same within a factor of two or less when converted separately. Thus, vapor equilibrium plays a role for the conversion of the heavier alkanes and in this case the conversion essentially occurs with only the compound present in the liquid phase. The single branched cracked products show a peak at the mid-carbon number, C8 and C14 for the two reactants, but the peak for the multi-branched product occurs at a higher carbon number. Thus, it appears that the multi-branched products are primarily produced in a series reaction with the singly branched compounds being formed as the primary products. The data for wax conversion are consistent with the competitive conversion operating for the higher carbon number compounds; however, the transport of intermediate carbon number products from the reactor occurs more rapidly than their formation rates by cracking reactions. The data clearly show that the hydrocracking of wax is dominated by vapor–liquid equilibrium and that hydrocracking is initially controlled by the compounds present in the liquid phase. Figure shows the catalyst pore filling with low boiling (left) and high boiling (right) hydrocarbons. Each reactant saturates the catalytic sites and the breaking of C–C bond occurs. Once the products from cracking of the liquid phase go into the vapor phase, it should rapidly pass the catalyst bed. This short contact time on gas phase hydrocarbons relative to the liquid phase, limits the conversion of low boiling point hydrocarbons.

Rheological and mechanical characterization of waste PMMA/ATH modified bitumen

Waste composite poly-methyl methacrylate filled with a fine dispersion aluminium trihydrate (PMMA/ATH) and Fischer–Tropsch wax were used as modifying agents for a 70/100 paving grade bitumen employed for road paving. The effect of modifying agent content, primary ageing and long-term oxidative ageing on rheological and mechanical properties of base and modified bitumen were studied. The rutting resistance at high service temperatures was analyzed with oscillatory shear tests and multiple stress creep recovery measurements. Waste PMMA/ATH powder proved suitable for bitumen modification, particularly in combination with wax. Moreover, aluminium trihydrate is a flame retardant material. PMMA/ATH is less susceptible to heat and oxygen, therefore modified bitumen samples show improved viscoelastic and physical characteristics compared to base bitumen at handling and in-service temperatures.

CO2 valorization: Production of synthetic gasoline and diesel fuel from dry reforming of methane

The purpose of this study is to illustrate the potential of dry reforming of methane for industrial applications by producing synthetic fuels from the combination of dry and steam reforming of methane. The proposed process includes four main units: production of synthesis gas from the dry and steam reforming of methane, Fischer Tropsch synthesis, hydro-cracking of Fischer Tropsch waxes, product upgrading and hydrogen recovery. Simulation model of this process was carried out with Aspen Plus software which allows us to define and analyze the optimum conditions and equipment specifications for each unit. Energy consumption and CO2 balance are also calculated. The main interest of our proposed process is its very favorable carbon balance.

Fluid catalytic cracking: Processing opportunities for Fischer–Tropsch waxes and vegetable oils to produce transportation fuels and light olefins

Fluid catalytic cracking (FCC) of Fischer–Tropsch (FT) waxes and vegetable oils could be an attractive option to produce transportation fuels and light olefins. For FT waxes, the catalytic cracking using commercial FCC catalysts revealed that a particular product slate (gasoline, diesel or light olefins) with high selectivity can be obtained by selecting an appropriate catalyst and operating conditions. FT wax is an outstanding feedstock in providing a high-value petrochemical feedstock, propene, with yields about 25wt.% by employing pure ZSM-5 or ZSM-5/FCC catalyst (Y-zeolite-based) mixture. Similar amounts of butenes are also obtained. For the catalytic cracking of vegetable oils, the product distribution primarily depends on the degree of unsaturation (double bonds) of vegetable oils. For gasoline with high selectivity, saturated vegetable oils are more preferable. Irrespective of the degree of unsaturation, the aromatic content of the product fractions is relatively high compared to those from the conventional FCC feedstocks (VGO). Further modification of a FCC catalyst with a suitable metal (nickel) along with co-feeding H2 tremendously increases the gasoline and light olefins yields from a vegetable oil. Thus, development of a novel catalyst and/or tuning catalyst characteristics is still a promising research area to focus onto improve the cracking performance of vegetable oils. The cracking data of FT waxes/vegetable oils with VGO showed that co-processing of renewable feedstocks with the conventional FCC feedstocks is promising and no significant interactions exist between conventional and renewable feedstocks. Consequently, the prediction of the cracking performance at different blend ratios is straightforward.

Comparative Study on Performance of Wax-Modified and Typical SMA Mixtures

Stone-matrix asphalt (SMA) is a type of hot-mix asphalt that can reduce the cost of maintenance and rehabilitation of pavements through decreasing the amount of permanent deformation during its service life. In addition, warm-mix asphalt (WMA) has been recently used to reduce the mixing and compaction temperatures of asphalt concrete and potentially decrease the initial cost of asphalt mixtures, especially in countries for which energy costs are high. The primary purpose of this research is to combine these technologies to produce more efficient asphalt mixtures. To this end, two different additives [cellulose fiber and styrene-butadiene-styrene (SBS)] were used to construct typical SMA mixtures, and a type of WMA additive (wax) was used to prepare warm SMA specimens. Modified binders were subjected to binder properties tests. Mixture performance tests, including the Marshall, indirect tensile strength, moisture susceptibility, dynamic creep, and resilient modulus tests were also performed to evaluate the performance properties of different types of SMA mixtures. A mechanistic-empirical design procedure was conducted to investigate the benefit of modification. The results indicate that Fischer-Tropsch (FT) wax is capable of enhancing the base binder properties. Although different percents of wax could reduce the amount of binder drain down, this reduction was not adequate. Consequently, the use of an additional additive may be necessary. The effect of wax on the performance properties of SMA mixtures was also insignificant, although there were some improvements. Moreover, by comparing the test results, good correlations were obtained between various performance properties of SMA mixtures, all of which were significant. The use of cellulose fiber, SBS, and FT wax would respectively increase the service life of the pavement 1.08, 1.243, and 1.154 times more than the corresponding unmodified mixtures.

Continuum lumping kinetics of complex reactive systems

Continuum lumping is a methodology widely used to describe the kinetic or thermodynamic behaviour of complex reactive mixtures of various components all undergoing similar types of reactions (e.g., cracking, pyrolysis, oligomerisation). The methodology is particularly convenient when the number of species involved is very large and the species can be characterised by properties that can be measured in a continuous fashion, as for instance in a chromatogram. By applying the lumping methodology, a large reactive system can be reduced to a simpler and more tractable one. In the present paper, the continuum lumping methodology is applied to the hydrocracking of Fischer–Tropsch waxes (n-paraffins), extending a previous model by Laxminarasimhan et al. (1996). Specifically, the role of the type-distribution function is investigated by employing two expressions of such function and by studying how it affects the model predictions. The effect of the operating conditions (namely temperature, pressure and hydrogen to feed ratio) on the hydrocracking process is also investigated. The model parameters are estimated by using experimental data obtained from a bench scale trickle bed reactor for specified ranges of operating conditions.

Synergies from combined pulp&paper and fuel production

In this paper, the prospect of integrating a combined paper&pulp mill with fuel production via biomass gasification was investigated. In the study, three different types of gasifiers (circulating fluidised bed, entrained flow and indirect gasification) and three fuel processes (dimethyl ether, methanol and Fischer-Tropsch wax synthesis) were investigated using computer simulations. The paper reports differences from the stand-alone cases and the integrated cases, using the electricity equivalence efficiency as a measure. Only 6 out of the 18 integrated cases studied displayed a positive result from integration and no obvious fuel selection that stand out as the most beneficial one, however the synthesis of dimethyl ether is, in combination with all gasifiers assessed a rather good choice, with an change in efficiency from integration ranging from −1% to 4%. Dimethyl ether is not the best choice if the electrical equivalence is to be maximised however. In this case the combination of circulating fluidised bed gasification and methanol synthesis should be pursued. The production of Fischer-Tropsch wax should according to the chosen measure not be produced; however there is an added value in the production of a non-oxygenated fuel which has not been taken into account in this particular study. All cases leads to a reduction of 0.4–0.9 kg CO 2 per kg of dry biomass used in the process for fuel synthesis and the possibility to export bark is a more significant factor in this respect than which type of fuel is synthesised. ► A system integration with three gasifier types used for synthesising three different synthetic fuels. ► Energy efficiencies and electrical equivalence efficiencies reported. ► Results differ and the benefit of integration is not given, only some of the investigated cases show synergies on integration.

Production of Synthetic Gasoline and Diesel Fuel from Dry Reforming of Methane

The dry reforming of methane produces synthesis gas from carbon dioxide and methane (CH4). Although this concept has many environmental and economic incentives, today it is not implemented in large plants. The purpose of this study is to illustrate the potential of dry reforming of methane for industrial applications by producing synthetic fuel from the combination of dry and steam reforming of methane. The proposed process includes four main units: production of synthesis gas from the dry and the steam reforming of methane, Fischer Tropsch synthesis, waxes hydro-cracking Fischer Tropsch waxes, product upgrading and hydrogen recovery. Simulation model of this process is carried out with Aspen Plus® software (Advanced System for Process Engineering) which allows us to define and analyze the optimum conditions and equipment specifications for each unit. Energy consumption and CO2 balance of this process are also calculated. The main interest of our proposed process is its very favorable carbon balance.

Low temperature hydrogenolysis of waxes to diesel range gasoline and light alkanes: Comparison of catalytic properties of group 4, 5 and 6 metal hydrides supported on silica–alumina

A series of metal hydrides (M = Zr, Hf, Ta, W) supported on silica–alumina were studied for the first time in hydrogenolysis of light alkanes in a continuous flow reactor. It was found that there is a difference in the reaction mechanism between d0metal hydrides of group 4 and d0 ↔ d2metal hydrides of group 5 and group 6. Furthermore, the potential application of these catalysts has been demonstrated by the transformation of Fischer–Tropsch wax in a reactive distillation set-up into typical gasoline and diesel molecules in high selectivity (up to 86 wt%). Current results show that the group 4 metal hydrides have a promising yield toward liquid fuels.

Upgrading of Fischer–Tropsch Waxes by Fluid Catalytic Cracking

Synthesis gas originating from alternative feedstocks such as biomass, coal, or natural gas can become an important source of hydrocarbon-based automotive fuels in the future. Fischer–Tropsch synthesis (FTS) affords these hydrocarbons, but upgrading of the primary FTS products is unavoidable. One option is to use the fluid catalytic cracking (FCC) process to convert FTS waxes into a wide range of products. To investigate the impact of FTS wax addition to a conventional FCC feedstock on product yields and properties, microactivity test (MAT) experiments were performed. The tests were performed at 803 K and the catalyst to feed ratio (C/F) was varied in the range 2–4 m/m. The feed contained 0–100% of FTS wax. The addition of FTS wax resulted in increased conversion and yield of the middle distillate fraction (light cycle oil, LCO) and decreased yield of coke. Owing to the increased conversion, higher yields of propylene were obtained by catalytic cracking of feedstocks containing FTS wax. The detailed GC analysis of the products indicated enhanced properties of LCO due to the lowered content of aromatics.

Structural and rheological characterization of wax modified bitumens

The research focuses on the use of waxes as asphalt modifiers. Bitumen/wax blends were produced by addition of controlled quantities of different type of wax to a 70/110 unmodified bitumen. Five different waxes were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-modified waxes. Blends were subjected to different rheometric and thermal testing to relate their characteristics with those of the wax in temperature ranges of technical interest. It was found that bitumen/wax blends have a peculiar and quite complex mechanical response, connected with the melting/crystallizing properties of the wax and the degree of residual crystallinity into the blend. The effects of wax on the binder rheology were found to be mainly controlled by the compositional characteristics of the wax. The experimental program carried out provides different indications for the development of the warm mix asphalt technology and for the general evaluation of wax modification of asphalt binders.

Thermally conductive phase-change materials for energy storage based on low-density polyethylene, soft Fischer–Tropsch wax and graphite

Phase change materials based on graphite-filled wax/polyethylene blends could find application as thermal energy storage materials. Such compounds, comprising wax to polyethylene in a 3:2 proportion, were prepared by twin screw compounding. Two types of graphite were used in an attempt to improve the thermal conductivity of the compounds. Expanded graphite enhanced the thermal conductivity by more than 200% at a loading of 10 wt.%, compared to a ca. 60% improvement with natural graphite flakes at the same loading. The TGA results showed that all the compounds underwent a two-step degradation. In all cases the mass % ratios of the two degradation steps were roughly 3:2 for wax:LDPE, which confirms that the wax evaporated completely before the degradation of LDPE started. The DSC results suggest that the heat energy storing capacity of the wax is not influenced by the other components as long as heating is restricted to temperatures just above the melting point of the wax. It is also apparent that the presence of both forms of graphite enhanced the rate of heat transfer to the PCMs. The DMA results show that the presence of wax had a softening effect, while the presence of graphite opposed this softening effect by reinforcing the PCM composites.

INVESTIGATION OF CATALYTIC CONVERSION OF FISCHER-TROPSCH WAX ON Pt/AlSBA-15 AND Pt/BETA ZEOLITE CATALYSTS

Because of the more serious problems with the environment (e.g. greenhouse effect) and the crude oil supply (e.g. import dependence) the use of fuels and lubricants produced from renewable feedstocks have come to the front nowadays. The Fischer-Tropsch wax (60–80% of the Fischer-Tropsch products) which is produced on synthesis gas from different sources (biological or waste), is a mixture of high molecular weight (C20-C60) n-paraffins, which are in solid state (high pour point) at normal conditions. The products (fuels and base oils) which can be produced from this paraffin mixture have high quality and have fewer negative effects on the environment (practically zero sulphur- and nitrogen content, low aromatic content, excellent application properties) thus theydo not demand changes in the fuel supply infrastructure and in the engine constructions. The isomerization of high molecular weight n-paraffins can be effectively carried out on bifunctional catalysts. There are only a few indications about the application of metal catalysts on mesoporous carrier in the literature. Consequently our objective was to investigate some Pt/AlSBA-15 (SBA: Santa Barbara Amorphous) catalysts which have not been investigated in detail in this reaction system yet, and compare its properties with a Pt/beta zeolite catalyst which has been recommended for this reaction earlier. The applicability and catalytic activity of Pt/AlSBA-15 and Pt/beta zeolite catalysts of 0.5% platinum content for the selective isomerization of Fischer-Tropsch wax was investigated in the present experiment. The experiments werecarried out in a high-pressure microreactor system in continuous operation and on a catalyst with steady-state activity. The main properties of the feedstock which was a mixture of paraffin produced by Fischer-Tropsch synthesis (the synthesis gas was produced from biomass) were: n-paraffin content (C18-C57): 97.4%, sulphur content: 5 mg/kg, pour point: 72 °C. In the experiment the following process parameters were applied: T=275–375 °C, P=40–80 bar, LHSV=1.0–3.0 h-1, H2/hydrocarbon ratio: 400–800 Nm3/m3. The composition of the products was determined by gas chromatography. From the catalysts with different support the best results were gained on the catalysts with AlSBA-15 support, and with increasing temperature the yield of liquid products (C5+) decreased, but until 325 °C this value was above 93% in every case. Incase of the beta zeolite high amount of cracking took place. Increasing the pressure shifted back the hydrocracking reactions(with the increasing number of moles) so it had a decreasing effect on the volume of the gas products and the lower contact time (higher liquid hour space velocity) had the same effect. In the gas products mainly branched isobutane was identified, which indicated that the cracking enacted partly after the isomerization reactions. The isoparaffin contents of the liquid products in the function of process parameters increased with increasing temperature and decreased with increasing pressure and LHSV in every case while other parameters were kept constant. Based on the isoparaffin contents of the different fractions it can be concluded that on Pt/AlSBA-15 catalyst at advantageous process parameter combinations (T=300–325 °C (C11-C20)/ 275–300 °C (C21-C30), P=40–80 bar, LHSV=1.0–2.0 h-1) the catalyst was applicable to produce C11-C20 and C21-C30 fractions with high isoparaffin content (63.5–85.6% and 34.1–58.7%) with adequate yields (29.9–36.6% and 46.2–58.8%). We experienced that the gas oil fractions having the lowest pour point were obtained in the case of high concentrations of 5-methyl isomers. The C21-C30 fraction is a high viscosity index (VI ≥125) base oil. The selectivity of the target product fractions was high, and based on these facts the selective isomerization of the Fischer-Tropsch wax can be a new application area of the Pt/AlSBA-15 catalyst.

Hydroisomerization of Fischer–Tropsch Wax on Pt/AlSBA-15 and Pt/SAPO-11 Catalysts

A Pt/AlSBA-15 catalyst was investigated in the selective isomerisation of Fischer–Tropsch wax, which type of catalyst have not been studied in detail in this reaction system yet. Its hydroconversion activity was compared with that of the Pt/SAPO-11 catalyst. Based on the results it was concluded that the selective isomerization of the Fischer–Tropsch wax can be a new application of the Pt/AlSBA-15 catalyst.

Rheological characterization of wax-modified asphalt binders at high service temperatures

The research reported herein focuses on the rheological characterization of wax-modified asphalt binders used in warm mix asphalt (WMA) technology. Wax-modified asphalt binders were produced by adding controlled quantities of different types of wax to a 50/70 unmodified bitumen. Five different kinds of wax were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-modified waxes. All the blends were subjected to different rheometric tests to assess their mechanical response at high service temperatures. The viscous deformation mechanism was analyzed with reference to static and repetitive creep loading; it was found that the viscous deformation is strongly affected by the presence of both hydrocarbons and amidic-modified waxes. Wax-modified binders exhibited an effective improvement in intrinsic resistance to non-reversible deformation, even in high applied stress and cyclic loading conditions. It was observed that the chemical composition and the consequent physical characteristics of the wax are the most important factors regulating the final behavior of wax-modified asphalt binders at high service temperatures. The final contribution of the experience performed is related to the technical evaluation of wax-modified asphalt binders and to the general development of WMA technologies for pavement applications.

Improved bondability of wax-treated wood following plasma treatment

In this study, the impact of a plasma treatment using dielectric barrier discharge at atmospheric pressure on wax-treated beech was investigated by surface energy determination and adhesion tests. Measurements of the surface energy revealed a strong increase in surface polarity along with increased surface energy as a result of the plasma treatment, pointing to increased adhesion properties. To evaluate the adhesion properties of a polyvinyl acetate (PVAc) adhesive on beech treated with montan ester wax and synthetic Fischer–Tropsch wax, a special peel test was applied. This peel test provided evidence of increased adhesion of the PVAc after plasma treatment of both materials investigated.

Liquid fuels from Fischer–Tropsch wax hydrocracking: Isomer distribution

Considering the current need of low emission fuels for the automotive market and the need of renewable fuels that will emerge in the very next future, Fischer–Tropsch (FT) based technologies should be considered a valid option to accomplish both low emission and renewable fuel production targets. A hydrocracking step is necessary for obtaining high quality fuels from FT wax. Isomerisation is an important reaction that takes place during the hydroconversion process. The amount and the type of the isomers in the produced fuels heavily influence both cold flow properties and cetane number. In this paper the results of a detailed method of analysis which allows the distinction between mono-branched and multi-branched isomers in fuels obtained from an FT wax hydrocracking process, are presented and discussed. In particular the influence of the operating conditions and the wax conversion on the isomer distribution is pointed out.

H2S Effects in Base-Metal-Catalyzed Hydrocracking of Fischer−Tropsch Wax

The effect of H2S on catalyst activity and product selectivity during hydrocracking of Fischer−Tropsch (FT) wax was studied using sulfided silica−alumina-supported NiMo and NiW catalysts. FT wax, which is sulfur free was hydrocracked at various H2S concentrations by addition of dimethyl disulfide (DMDS). Conversion and selectivity were affected by the reaction temperature and H2S concentration. On the basis of the classical hydrocracking mechanism, the observed variations in product selectivity were attributed to the change in the ratio of metal to acid sites, which was affected by H2S addition. Catalyst deactivation in commercial practice is compensated by increasing the operating temperature, but higher reaction temperatures create more unsulfided metal sites, which on the other hand result in catalyst selectivity changes. This effect has to be balanced by adjusting the H2S concentration accordingly.

Selective Hydrocracking of Fischer–Tropsch Waxes to High-quality Diesel Fuel Over Pt-promoted Polyoxocation-pillared Montmorillonites

Polyoxocation ([AlO4Al12(OH)24(H2O)12]7+ and [Zr4(OH)14(H2O)10]2+)-pillared montmorillonites were prepared by ion exchange, and they were used as solid acid catalysts, in comparison to some other solid acids, for the selective hydrocracking of Fischer–Tropsch waxes to diesel-ranged hydrocarbons. XRD patterns and elemental analyses proved that the polyoxocations were successfully introduced into the interlayer region of the montmorillonites. N2 adsorption–desorption measurement indicated that polyoxocation-pillared montmorillonites have large BET surface areas (>230 m2 g−1), high thermal stability (>673 K), and large pores (comparing to those in zeolites). FT-IR spectra of chemisorbed pyridine indicated that polyoxocation-pillared montmorillonites possess both Lewis and Bronsted acid sites on the solid surface. Temperature-programmed desorption of ammonia indicated that the acidity strength of the polyoxocation-pillared montmorillonites was weaker than those of H–ZSM-5, H–Y, WO3/ZrO2, and Al2O3–SiO2. In the hydrocracking of Fischer–Tropsch (F–T) waxes, the acidity strength of the solid acids in bifunctional catalysts greatly influences the product composition. Pt-promoted H–Y afforded a high yield of gasoline-ranged hydrocarbons (>90%) while Pt-promoted H–ZSM-5 afforded a larger amount of gas products due to its strong solid acid sites. On the other hand, among various catalysts, Pt-modified polyoxocation-pillared montmorillonites afforded the highest yield of diesel-ranged hydrocarbons (>70%) due to the appropriately weak acid strength, high thermal stability, large BET surface area, and large pore size. Pt is necessary for the hydrocracking of F–T waxes because it enables hydrogenation/dehydrogenation. However, a high Pt loading on the catalyst produces more light hydrocarbons due to the stimulation of hydrogenolysis. High hydrogen pressure improved the selectivity for diesel-ranged hydrocarbons but decreased the conversion of F–T waxes due to the suppression of alkane dehydrogenation. The hydrocracking of F–T waxes at a low temperature with a large amount of catalyst for longer reaction time increased the yield of diesel-ranged hydrocarbons.