Light Hydrocarbon Feedstock Research Articles

Influence of aluminum zoning toward external surfaces in MFI zeolites on propene oligomerization catalysis.

Brønsted acid zeolites catalyze alkene oligomerization reactions, an important route to produce fuels and chemicals from light hydrocarbon feedstocks. Propene dimerization rates (per H+, 503 K) decrease monotonically with increasing crystallite size in MFI zeolites because heavy oligomer products remain occluded within microporous voids and restrict intrazeolite diffusion of reactants and products. Here, we show that the preferential zoning of framework Al centers and their associated H+ sites toward exterior surfaces of MFI crystallites in an "egg-shell" architecture minimizes the extent of diffusion-enhanced secondary reactions within a given crystallite, which increases both propene dimerization rates (per H+) and selectivity to true oligomer products. These results show that tailoring Al distributions to be spatially zoned toward external surfaces of medium-pore zeolite crystallites is efficacious at minimizing diffusion path lengths to increase alkene oligomerization rates and selectivity to true oligomer products.

CO2-Selective Capture from Light Hydrocarbon Mixtures by Metal-Organic Frameworks: A Review

CO2 represents a typical impurity in light hydrocarbon feedstocks, which affects the quality of subsequent chemical products. Owing to their highly similar nature, industrial separation requires large amounts of energy. Adsorptive gas separation based on porous materials is considered an efficient alternative, as it can offer faster kinetics, higher selectivity, long-term stability and more energy-efficient regeneration. For the adsorption separation method, preferential CO2 capture from gas mixtures in one step is more energy-efficient for direct purification than light hydrocarbons, saving about 40% energy by eliminating energy-intensive post-regeneration processes such as countercurrent vacuum blowdown. Therefore, CO2-selective adsorbents are more sought-after than light hydrocarbon-selective adsorbents. Metal-organic frameworks (MOFs) have been demonstrated as outstanding physisorbents for CO2 capture due to their configurable channels for CO2 recognition, structural flexibility and large specific surface area. Many highly selective CO2 adsorption behaviors of MOFs have been reportedly achieved by precise modulation of pore size, pore chemistry or structural flexibility. In this review, we discuss the emerging development of MOFs for CO2-selective capture from different light hydrocarbon mixtures. The challenges of CO2 recognition and the strategies employed to achieve CO2 selectivity over light hydrocarbon mixtures by MOFs are summarized. In addition, the current challenges and prospects in the field of MOFs for CO2 capture are discussed and elaborated.

Improving the Operational Efficiency of Ethylene Cracking Integrated with Refining by Molecular Management

A new methodology for improving the operational efficiency of ethylene cracking integrated with refining is proposed. In this work, ethylene feedstock optimization was achieved by screening the low-value materials and naphtha in the refinery through the molecular management approach. The process synthesis-intensification model for ethylene production was developed to identify the opportunities for improving operational efficiency. The P-graph method was applied to accelerate problem solving and generate process routes with the objective function of economic gross potential. To determine the optimal process route, the comprehensive operational efficiency index and light hydrocarbon feedstock ratio were further constructed for process route evaluation. A case study of a real ethylene-refining integrated complex indicates that the proposed method could effectively optimize the operational efficiency of ethylene production and that the economic and inherent safety performances could be notably increased by 22.34% and 67.81%, respectively.

Regeneration Process for Coiled Iron-Oxide Cinder

The regeneration process for coked iron-oxide cinder, which has been proposed as an Effective contact (heat carrier) for thermal pyrolysis of light hydrocarbon feedstock, was studied. Oxidative regeneration of cinder at various temperatures was researched. The regeneration of the coked contact (determination of the dependence of the degree of coke burnout on time) was described mathematically. The reactivity of the coked cinder during oxidation by atmospheric oxygen was compared to those of other catalysts. Dynamic mass changes of the coked cinder were also investigated using dynamic thermogravimeny on a derivatograph. The main features of the contact mass changes as functions of time, temperature, and temperature rise rate during its oxidation by atmospheric oxygen were found. Research on multiple pyrolysis/regeneration cycles proved that the iron-oxide cinder could be used cyclically as a heat carrier for thermal contact pyrolysis. The yields of the target products remained constant.

Катализаторы на основе цеолитов и цеолитоподобных материалов для переработки легкого углеводородного сырья в компоненты моторных топлив

Катализаторы на основе цеолитов и цеолитоподобных материалов для переработки легкого углеводородного сырья в компоненты моторных топлив

Potential Cracking in Hydrogen Plant with Light Feedstocks (Part II)

This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.

Experience with Hydrogen-Free Treatment to Remove Sulfur Compounds from Light Hydrocarbon Feedstock of the Novokuibyshevsk Petrochemical Company

We have developed technology for hydrogen-free removal of sulfur compounds (H2S + RSH + COS + CH3–S–CH3) from wide cut light hydrocarbon fractions (WCLHs) and target products (C3, C4, iso-C5, n-C5) of gas-fractionation plants, including base-catalysis treatment to remove hydrogen sulfide and mercaptans from WCLHs, utilizing the homogeneous catalyst IVKAZ; removal of carbonyl sulfide from propane with hot alkali and regeneration of the alkali; removal of dimethyl sulfide from isopentane by azeotropic distillation; oxidative catalytic treatment of sulfur-containing alkaline wastes using the homogeneous catalyst IVKAZ. The obvious advantages of the homogeneous catalyst IVKAZ compared with the heterogeneous phthalocyanine catalysts KS and KSM in demercaptanization of light hydrocarbon feedstock and oxidative treatment of sulfur-containing alkaline wastes has been proven in practice.

Experience with the operation of units at the Omsk Oil Refinery for removing sulfur compounds from the butane-butylene fraction and waste water with the use of homogeneous and heterogeneous catalysts

Data is reported that attests to the successful operation of the butane-butylene fraction demercaptanizing unit of the gas fractionating section of the KT-1/1 plant and the unit for demercaptanizing the unsaturated stabilizer overhead stream (reflux) of the gas purifying and gas fractionating section of the catalytic cracking plant 43-103. In the demercaptanization process, the alkali solution was regenerated using homogeneous catalyst of the trademark IVKAZ. The obvious advantages of IVKAZ homogeneous catalyst over heterogeneous catalyst of the trademark KSM were proved in practice in the processes of light hydrocarbon feedstock demercaptanization and oxidative purification of sulfurous-alkaline effluents. The degree of alkali solution regeneration reaches 95% in the presence of IVKAZ catalyst, whereas it is only 30% on KSM catalyst.

Tandem sulfur chemiluminescence and flame ionization detection with planar microfluidic devices for the characterization of sulfur compounds in hydrocarbon matrices

The detection of sulfur compounds in different hydrocarbon matrices, from light hydrocarbon feedstocks to medium synthetic crude oil feeds provides meaningful information for optimization of refining processes as well as demonstration of compliance with petroleum product specifications. With the incorporation of planar microfluidic devices in a novel chromatographic configuration, sulfur compounds from hydrogen sulfide to alkyl dibenzothiophenes and heavier distributions of sulfur compounds over a wide range of matrices spanning across a boiling point range of more than 650°C can be characterized, using one single analytical configuration in less than 25min. In tandem with a sulfur chemiluminescence detector for sulfur analysis is a flame ionization detector. The flame ionization detector can be used to establish the boiling point range of the sulfur compounds in various hydrocarbon fractions for elemental specific simulated distillation analysis as well as profiling the hydrocarbon matrices for process optimization. Repeatability of less than 3% RSD (n=20) over a range of 0.5–1000 parts per million (v/v) was obtained with a limit of detection of 50 parts per billion and a linear range of 0.5–1000 parts per million with a correlation co-efficient of 0.998.

Steam reforming of propane in a fluidized bed membrane reactor for hydrogen production

Steam reforming of propane was carried out in a fluidized bed membrane reactor to investigate a feedstock other than natural gas for production of pure hydrogen. Close to equilibrium conditions were achieved inside the reactor with fluidized catalyst due to the very fast steam reforming reactions. Use of hydrogen permselective Pd 77Ag 23 membrane panels to extract pure hydrogen shifted the reaction towards complete conversion of the hydrocarbons, including methane, the key intermediate product. Irreversible propane steam reforming is limited by the reversibility of the steam reforming of this methane. To assess the performance improvement due to pure hydrogen withdrawal, experiments were conducted with one and six membrane panels installed along the height of the reactor. The results indicate that a compact reformer can be achieved for pure hydrogen production for a light hydrocarbon feedstock like propane, at moderate operating temperatures of 475–550 °C, with increased hydrogen yield.

Study of properties of coked iron catalysts for pyrolysis of lower hydrocarbons

The electrophysical properties of spent iron catalysts coked during the pyrolysis of light hydrocarbon feedstock were studied. The remanent magnetization, saturation magnetization, and coercive force of samples with different fractional compositions were determined over the frequency range up to 1 MHz. The magnetic properties of the carbon-catalyst system were studied over the microwave frequency range up to 9.6 GHz.

Steam Reforming of Sunflower Oil over Ni/Al Catalysts Prepared from Hydrotalcite-Like Materials

Using catalytic steam reforming of biofuels to produce hydrogen for energy systems based on fuel cells is an option that may help to reduce the net emissions of CO2 into the atmosphere. Vegetable oils are some of the most interesting options because of their high potential yield of hydrogen. They are, however, more difficult to reform than the light hydrocarbon feedstocks that are used for producing hydrogen industrially by steam reforming. Catalysts prepared from hydrotalcite-like materials are promising for use in the steam reforming of vegetable oils, since their catalytic activity is significantly higher than that of commercial catalysts for hydrocarbon steam reforming. In this paper, a study is made of how the nickel content of HT-derived catalysts affects their activity for steam reforming of sunflower oil. Three catalysts were prepared with Ni/Al atomic ratios of 1, 2, and 3, respectively. The samples were characterized by various techniques to correlate their activity with the structural characteristics of the catalysts: X-ray diffraction (XRD), BET, thermogravimetric analysis (TGA), and hydrogen chemisorption. The results showed that the catalyst activity increased as the nickel content in the material decreased. The support and its properties seemed to play a key role in the performance of the HT-derived catalysts. This is probably because a decrease in the Ni content produces a better dispersion of the metal and higher BET areas, which leads to a higher capacity for water adsorption. With the most active catalyst (Ni/Al of 1), 2.2 mol H2/(gcat h) was produced at 575 °C, 2 bar, and a steam-to-carbon ratio of 3.

REACTOR-MEMBRANE PERMEATOR CASCADE FOR ENHANCED PRODUCTION AND RECOVERY OF H2 AND CO2 FROM THE CATALYTIC METHANE-STEAM REFORMING REACTION

The catalytic reforming of methane by steam is an important industrial process that produces H2, CO and CO2, thus chemically transforming natural gas, coal gas and light hydrocarbon feedstocks to synthesis gas or hydrogen fuel. Methane-steam reforming may consist of a number of reactions depending on the reforming catalyst, operating conditions and feedstock composition, The typical industrially desirable reactions are the reverse of methanation (CH4 + H2O = CO + 3H2) and the water-gas shift (CO + H2O = CO2 + H2). Both reactions are equilibrium limited and the composition of the mixture that exits the reformer is in accordance with the one calculated thermodynarmically. Removal of reaction products at the reactor exit by means of selective membrane permeation can offer improved CH4 conversions and CO2 and H2 yields, assuming the subsequent utilization of the reject streams by a second methane-steam reformer. We numerically investigated the feasibility of a system of two tubular methane-steam reformers, in series with an intermediate permselective polyimide membrane permeator, as means of improving the overall CH4 conversion and the H2, CO2 yields over conventional methane-steam reforming equilibrium reaction-separation schemes that are currently in industrial practice. The unique feature of the permselective polyimide separator is the simultaneous removal of H2 and CO2 versus CH4 and CO from the reformed streams. The utilized 6FDA-3,3′, 5,5′-TMB aromatic polyimide was reportedly characterized [10] and found to exhibit superior permselective properties compared with other polyimides of the same or different dianhydride sequence. Conversion and yield of the designed reactor-membrane permeator reforming system can be maximized by optimizing the permselective properties of the membrane material and the design variables of the reactors and the permeator. Product recovery and purity in the permeate stream need to be compromised to overall enhance methane conversion and product yield. The operating variables that were varied to investigate their effect on the magnitude of conversion and yield included the inlet pressure of the first reformer, the temperature of both reformers, and the permeator dimensionless Pe' number (variation of the first two variables results to a drastic change in the composition of the reformed stream that enters into the permeator). The numerical results show that the new reformer-membrane permeator cascade process can be more effective (it can offer increased CH4 conversions and H2, CO2 yields) than conventional equilibrium methane-steam reforming reaction-separation processes currently in practice.

Heterogeneous catalytic demercaptization of light hydrocarbon feedstock

Heterogeneous catalytic demercaptization of light hydrocarbon feedstock

Catalyst complex for demercaptization of light hydrocarbon feedstocks

Catalyst complex for demercaptization of light hydrocarbon feedstocks

Methane-Steam Reforming

Abstract For more than 40 years the catalyzed hydroearbon-steam reforming reaction has been of commercial value. The first units commissioned in the 1930s were run on light hydrocarbon feedstock at atmospheric pressure [l], It took until 1962 for a 15-atm steam reformer to come on-stream in the United Kingdom using liquid hydrocarbon feedstock [2–4].

Gas chromatographic detection and identification of aromatic and aliphatic hydrocarbons in complex mixtures by coupling photoionization and flame-ionization detectors

A technique has been developed that is based on analyzing the effluent from a gas chromatograph with both photoionization (PID, with 10.2-eV lamp) and flame-ionization (FID) detectors. The relative molar response per mole of carbon (RMR) for the FID is similar for many types of carbon atoms, e. g., aromatic and aliphatic and therefore the FID is used to measure the relative levels of a particular hydrocarbon regardless of the degree of saturation. The RMR for the PID, however, increases with unsaturation. A ten-fold difference is observed between aromatics and alkanes, and the alkene response on the PID is midway between these two classes of compounds. When the PID and FID responses ( i. e., peak areas) are normalized to any alkene ( e. g, n-hexane) and are compared, those compounds with a normalized PID/FID ratio of 2–4 are alkenes, those with a ratio of 5–10 are aromatics and those with similar ratios (<2) are alkanes. Preliminary work on this technique was started with simple hydrocarbon mixtures, then extended to high-molecular-weight heteroatom molecules such as chlorinated and sulfur-based pesticides. Finally, a practical application of this approach was demonstrated with the successful analysis of aromatics in a light hydrocarbon feedstock for a synthetic natural gas plant. This technique should prove useful for analyses (nanogram levels) and for the identification of complex hydrocarbon mixtures.

Profitability in production of light hydrocarbon feedstock in the petroleum refining industry

Profitability in production of light hydrocarbon feedstock in the petroleum refining industry

C&amp;EN Talks With...

Despite the political and economic confusion about future petrochemical feedstock availability, a rough dogma is emerging. Oversimplified, the new logic goes like this. New olefins plants will all use heavier, oil-derived feedstocks in contrast to the light hydrocarbon feedstocks currently obtained from natural gas. This switch will result in a large increase of heavier olefins produced as coproducts of the big item, ethylene. At the same time, changes in gasoline production at oil refineries, such as not adding lead, also will affect refinery-produced petrochemical feedstocks. Two important feedstock shifts here could be increased availability of refinery propylene and decreased availability of refinery aromatics such as benzene. Every part of this dogma could turn out to be wrong, thinks a man in one of the key feedstock observing posts in the U.S., Leo H. Johnstone, executive vice president for chemicals at Phillips Petroleum. He questions some of the major assumptions in the new feedstock rhetoric. Ab...

Analysis of efficiency in producing light hydrocarbon (LPG) feedstocks in refineries, gas processing plants, and central gas fractionating units

1. When account is taken of the savings to the consumer, the production of LPG in the central gas fractionating unit of a petrochemical combine is more efficient. 2. Of the schemes that have been examined for central gas fractionation units Nos. 1 and 2, the more effective is that of No. 2. 3. When it is considered that in the future all gas fractionation units will be built with flow plans to provide maximum LPG recovery coefficients and the production of individual hydrocarbons conforming to Grade A of the MRTU-67 specification, questions of where to locate gas fractionation units must be resolved on the basis of the costs involved in transporting the LPG to the consumer and the savings to be achieved by the use of these materials in the chemical and petrochemical industry.