Propylene Production Research Articles

Methane, ethane, and propane production in Greenland ice core samples and a first isotopic characterization of excess methane

Abstract. Air trapped in polar ice provides unique records of the past atmospheric composition ranging from key greenhouse gases such as methane (CH4) to short-lived trace gases like ethane (C2H6) and propane (C3H8). Recently, the comparison of CH4 records obtained using different extraction methods revealed disagreements in the CH4 concentration for the last glacial in Greenland ice. Elevated methane levels were detected in dust-rich ice core sections measured discretely, pointing to a process sensitive to the melt extraction technique. To shed light on the underlying mechanism, we performed targeted experiments and analyzed samples for methane and the short-chain alkanes ethane and propane covering the time interval from 12 to 42 kyr. Here, we report our findings of these elevated alkane concentrations, which scale linearly with the amount of mineral dust within the ice samples. The alkane production happens during the melt extraction step of the classic wet-extraction technique and reaches 14 to 91 ppb of CH4 excess in dusty ice samples. We document for the first time a co-production of excess methane, ethane, and propane, with the observed concentrations for ethane and propane exceeding their past atmospheric background at least by a factor of 10. Independent of the produced amounts, excess alkanes were produced in a fixed molar ratio of approximately 14:2:1, indicating a shared origin. The measured carbon isotopic signature of excess methane is (-47.0±2.9) ‰ and its deuterium isotopic signature is (-326±57) ‰. With the co-production ratios of excess alkanes and the isotopic composition of excess methane we established a fingerprint that allows us to constrain potential formation processes. This fingerprint is not in line with a microbial origin. Moreover, an adsorption–desorption process of thermogenic gas on dust particles transported to Greenland does not appear very likely. Instead, the alkane pattern appears to be indicative of abiotic decomposition of organic matter as found in soils and plant leaves.

Promoting active site renewal in heterogeneous olefin metathesis catalysts.

As an atom-efficient strategy for the large-scale interconversion of olefins, heterogeneously catalysed olefin metathesis sees commercial applications in the petrochemical, polymer and speciality chemical industries1. Notably, the thermoneutral and highly selective cross-metathesis of ethylene and 2-butenes1 offers an appealing route for the on-purpose production of propylene to address the C3 shortfall caused by using shale gas as a feedstock in steam crackers2,3. However, key mechanistic details have remained ambiguous for decades, hindering process development and adversely affecting economic viability4 relative to other propylene production technologies2,5. Here, from rigorous kinetic measurements and spectroscopic studies of propylene metathesis over model and industrial WOx/SiO2 catalysts, we identify a hitherto unknown dynamic site renewal and decay cycle, mediated by proton transfers involving proximal Brønsted acidic OH groups, which operates concurrently with the classical Chauvin cycle. We show how this cycle can be manipulated using small quantities of promoter olefins to drastically increase steady-state propylene metathesis rates by up to 30-fold at 250 °C with negligible promoter consumption. The increase in activity and considerable reduction of operating temperature requirements were also observed on MoOx/SiO2 catalysts, showing that this strategy is possibly applicable to other reactions and can address major roadblocks associated with industrial metathesis processes.

Mesoporous Chromium Catalysts Templated on Halloysite Nanotubes and Aluminosilicate Core/Shell Composites for Oxidative Dehydrogenation of Propane with CO2

The oxidative dehydrogenation of alkanes is a prospective method for olefins production. CO2-assisted propane dehydrogenation over metal oxide catalysts provides an opportunity to increase propylene production with collateral CO2 utilization. We prepared the chromia catalysts on various mesoporous aluminosilicate supports, such as halloysite nanotubes, nanostructured core/shell composites of MCM-41/halloysite (halloysite nanotubes for the core; silica of MCM-41-type for the shell), and MCM-41@halloysite (silica of MCM-41-type for the core; halloysite nanotubes for the shell). The catalysts have been characterized by X-ray fluorescence analysis, low-temperature nitrogen adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of ammonia, transmission electron microscopy with energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The catalysts’ performance in carbon-dioxide-assisted propane dehydrogenation has been estimated in a fixed-bed reactor at atmospheric pressure. The most stable catalyst is Cr/halloysite, having the lowest activity and the largest pore diameter. The catalyst, Cr/MCM-41/HNT, shows the best catalytic performance: having the highest conversion (19–88%), selectivity (83–30%), and space–time yield (4.3–7.1 mol C3H6/kg catalyst/h) at the temperature range of 550–700 °C. The highest space–time yield could be related to the uniform distribution of the chromia particles over the large surface area and narrow pore size distribution of 2–4 nm provided by the MCM-41-type silica and transport channels of 12–15 nm from the halloysite nanotubes.

Bioglycerol-to-Propylene Routes: From Fundamental Catalysis to Process Design and Marketing

Bioglycerol-to-propylene (GTP) routes are undergoing major developments in terms of both fundamental catalysis and process design on the way to becoming a connecting bridge between the biorefinery and polyolefin industries. This review starts introducing some GTP routes-related market potentialities and continues discussing significant mechanistic, kinetic, and engineering developments in GTP catalysis involving high-temperature, multistep, tandem, and single-step hydrodeoxygenation strategies. It highlights the main advances made in the design of efficient catalysts and in the elucidation of their active sites, thereby shedding light on state-of-the art preparation, functionalization, and characterization methods. The GTP mechanisms are also assessed over versatile metallic, acid, and bifunctional catalysts’ surfaces to discover which C–O bond is removed and which C=C bond is formed. GTP configurations are discussed as a function of the thermodynamic and operating conditions affecting catalysts’ reactivity, selectivity, and stability. They are also compared using various qualitative and quantitative criteria such as process configuration, severity of operating conditions, energy consumption, sustainability assessment, and propylene production. We thus intend to provide a broad overview of GTP catalysis for inducing new opportunities in the biorefinery-to-olefins field.

Thermodynamic analysis of bio-oil model compounds to light hydrocarbon

The present work uses the total Gibbs free energy minimization approach to analyze the thermodynamic equilibrium analysis of bio-oil model compounds to light hydrocarbons. A mixture of model compounds was subjected to co-cracking with methanol and ethanol, and at a range of temperatures (300–1200 °C) and pressures (1–50 bars), the equilibrium compositions were calculated as a function of the hydroxypropanone-acetic acid-ethyl acetate/methanol ratio (HAEM) and the hydroxypropanone-acetic acid-ethyl acetate/ethanol ratio (HAEE). Possible reactions were analyzed, revealing that methane is the predominant product, followed by hydrogen, carbon monoxide, carbon dioxide, and propionic acid. The production of light hydrocarbons, including ethylene, ethane, propylene, and propane, was minimal. Notably, the co-reactant ethanol (HAEE 1:12) in the co-cracking of bio-oil model compounds demonstrated a significant effect on the production of methane, ethylene, and propylene at 1 bar pressure and 300 °C (for methane production) and 1200 °C (for ethylene and propylene production).

Steam cracking of methyl ester: A modeling study on the influence of the hydrocarbon backbone

Biodiesel can be used to produce clean platform chemicals for the chemical industry, as an alternative to or blend with conventional steam cracking feedstocks. Research on the decomposition chemistry of biodiesel is crucial for understanding their combustion, aging and potential as source for base chemical production. Three methyl esters are studied with varying hydrocarbon chain length and a different degrees of saturation to evaluate the impact of these structural differences on the decomposition chemistry and the decomposition product composition. A new kinetic model is developed with the automatic kinetic model generation tool Genesys for the pyrolysis of methyl butanoate, methyl decanoate and methyl dec-4-enoate. New ab initio calculations are carried out for the pyrolysis of methyl butanoate and for retro-ene reactions in unsaturated hydrocarbons and methyl esters, because of their importance in the secondary decomposition chemistry. The first-principles based kinetic model is validated using in-house experimental data gathered in a tubular reactor and against literature experimental data gathered in a jet-stirred reactor for methyl decanoate pyrolysis. A rate of production analysis reveals the main channels towards the pyrolysis products. The presence of the double bond in the hydrocarbon chain leads to a higher production of aromatic species, at the cost of a lower ethylene and propylene production. The high selectivity to aromatics is caused by the fast formation of 1,3-cyclopentadiene from the unsaturated, resonantly stabilized radicals formed during the decomposition.

Regulating the C–H Bond Activation Pathway over ZrO2 via Doping Engineering for Propane Dehydrogenation

The efficient activation of the C–H bond in light alkanes and their catalyst design are significant for alkane-related catalytic processes in view of theoretical and practical aspects. Here, we report the C–H bond activation mechanism and structure–reactivity relationships of Ga-doped ZrO2 catalysts in propane dehydrogenation. Experimental and theoretical calculation results suggest that the introduction of Ga into the framework of ZrO2 alters the C–H bond activation pathway from a stepwise mechanism to a concerted mechanism involving simultaneous cleavage of two C–H bonds in propane, leading to a superior C–H bond activation ability and a lower reaction barrier than state-of-the-art metal oxide catalysts. In addition, a volcano-type dependence of the rate of propene formation on the Ga/Zr ratio is established due to a compromise of intrinsic activity and active site concentration. The strategy of metal incorporation into bulk metal oxide may provide an alternative solution to control the C–H bond activation pathway for efficient propene production.

Concerted oxygen diffusion across heterogeneous oxide interfaces for intensified propane dehydrogenation

Propane dehydrogenation (PDH) is an industrial technology for direct propylene production which has received extensive attention in recent years. Nevertheless, existing non-oxidative dehydrogenation technologies still suffer from the thermodynamic equilibrium limitations and severe coking. Here, we develop the intensified propane dehydrogenation to propylene by the chemical looping engineering on nanoscale core-shell redox catalysts. The core-shell redox catalyst combines dehydrogenation catalyst and solid oxygen carrier at one particle, preferably compose of two to three atomic layer-type vanadia coating ceria nanodomains. The highest 93.5% propylene selectivity is obtained, sustaining 43.6% propylene yield under 300 long-term dehydrogenation-oxidation cycles, which outperforms an analog of industrially relevant K-CrOx/Al2O3 catalysts and exhibits 45% energy savings in the scale-up of chemical looping scheme. Combining in situ spectroscopies, kinetics, and theoretical calculation, an intrinsically dynamic lattice oxygen “donator-acceptor” process is proposed that O2- generated from the ceria oxygen carrier is boosted to diffuse and transfer to vanadia dehydrogenation sites via a concerted hopping pathway at the interface, stabilizing surface vanadia with moderate oxygen coverage at pseudo steady state for selective dehydrogenation without significant overoxidation or cracking.

Effects of the FCC catalyst binder type on propylene production during catalytic cracking of VGO

Effects of the fluid catalytic cracking (FCC) catalyst binder type on catalytic properties were studied. SiO2 and Al2O3 were used for the FCC catalysts as a binder. Although the yield of olefins in gasoline, which is easily cracked to light olefins such as a propylene over the ZSM-5 additive, over the SiO2 binder catalyst was lower than that over the Al2O3 binder catalyst during vacuum gas oil (VGO) cracking, however, when the ZSM-5 additive was blended, the SiO2 binder catalyst showed higher propylene yield as compared with the Al2O3 binder catalyst. In terms of the difference in the properties of catalyst, the SiO2 binder catalyst indicated higher SAmicro than the Al2O3 binder catalyst after steaming. Moreover, the acid properties of the FCC catalysts after steaming also were affected by the binder type. In results, the SiO2 binder catalyst indicated higher propylene yield as compared with the Al2O3 binder catalyst.

Optimization and Control of Propylene Production by Metathesis of 2-Butene

This article considers the design and control of the 2-butene metathesis process. The process transforms a low-value feedstock derived from a fluid catalytic cracking unit into more valuable products. The economical optimization is applied to the preheat–reaction and separation sections, with the objective of minimizing the total annual cost. The dynamic response and control of the plant are evaluated for feed flow perturbations. Although the process control system acts as a first line of defense against potential hazards, other independent safety layers are discussed with safety limits specific to the critical equipment of the 2-butene metathesis unit. The results prove that the metathesis reaction of 2-butene over a mesoporous tungsten catalyst is economically attractive. For a 5.7 t/h feed rate consisting of 2-butene (70% molar) and n-butane (30% molar), a reaction–separation plant (without recycle) requires 6570 × 103 $ investment and has a profitability of 2300 × 103 $/year.

Research Progress on Propylene Preparation by Propane Dehydrogenation.

At present, the production of propylene falls short of the demand, and, as the global economy grows, the demand for propylene is anticipated to increase even further. As such, there is an urgent requirement to identify a novel method for producing propylene that is both practical and reliable. The primary approaches for preparing propylene are anaerobic and oxidative dehydrogenation, both of which present issues that are challenging to overcome. In contrast, chemical looping oxidative dehydrogenation circumvents the limitations of the aforementioned methods, and the performance of the oxygen carrier cycle in this method is superior and meets the criteria for industrialization. Consequently, there is considerable potential for the development of propylene production by means of chemical looping oxidative dehydrogenation. This paper provides a review of the catalysts and oxygen carriers employed in anaerobic dehydrogenation, oxidative dehydrogenation, and chemical looping oxidative dehydrogenation. Additionally, it outlines current directions and future opportunities for the advancement of oxygen carriers.

Coupling acid catalysis and selective oxidation over MoO3-Fe2O3 for chemical looping oxidative dehydrogenation of propane

Redox catalysts play a vital role in chemical looping oxidative dehydrogenation processes, which have recently been considered to be a promising prospect for propylene production. This work describes the coupling of surface acid catalysis and selective oxidation from lattice oxygen over MoO3-Fe2O3 redox catalysts for promoted propylene production. Atomically dispersed Mo species over γ-Fe2O3 introduce effective acid sites for the promotion of propane conversion. In addition, Mo could also regulate the lattice oxygen activity, which makes the oxygen species from the reduction of γ-Fe2O3 to Fe3O4 contribute to selectively oxidative dehydrogenation instead of over-oxidation in pristine γ-Fe2O3. The enhanced surface acidity, coupled with proper lattice oxygen activity, leads to a higher surface reaction rate and moderate oxygen diffusion rate. Consequently, this coupling strategy achieves a robust performance with 49% of propane conversion and 90% of propylene selectivity for at least 300 redox cycles and ultimately demonstrates a potential design strategy for more advanced redox catalysts.

Oxidation of Organic Compounds in Supercritical Fluid Conditions During Disposal of Industrial Waste Waters of Nizhnekamskneftekhim PJSC and Kazanorgsintez PJSC

The study performed on the supercritical aqueous oxidation of organic compounds in the water runoff of Nizhnekamskneftekhim PJSC, which was formed at the stage of epoxidation of propylene with ethylbenzene hydroperoxide during the joint production of propylene and styrene oxide, as well as run-off at PJSC "Kazanorginsez", when obtaining phenol and acetone from "Bisphenol-A" plant. The article studies a continuous operation mode on a flow reactor with induction heating (the drain from PJSC "Nizhnekamneftekhim") and periodic on coming from PJSC "Kazanorginsez". It was identified that close to complete oxidation in the presence of heterogeneous catalysts was achieved in a continuous mode at a temperature of 823 K and an excess of oxygen equal to 4.

Synergy between the proton conducting and a mixed electronic and oxygen ionic conducting phases in a composite anode for electrocatalytic propane ODH

Oxidative dehydrogenation (ODH) of propane offers an attractive and feasible method for increasing propylene production to meet the growing demand. In this study, a dual phase catalyst composed of proton conducting SrCe0.95Yb0.05O3 (SCY) and mixed oxygen ionic and electronic conducting (La0.8Sr0.2)0.95MnO3 (LSM) has been investigated for propane ODH. TPD-DRIFTS was used to study H2O adsorption and the presence of basic lattice oxygen on the surface of SCY. The addition of 40 wt% SCY to LSM resulted in significant improvements in propane conversion and olefin selectivity. These enhancements were likely due to the highly basic nature of the SCY surface by helping rapid desorption of propylene resulting in high propylene yields. In addition, proton conductive SCY facilitated the proton abstraction from propane and its transport to the interface between SCY and LSM where an oxidation reaction occurs. It was demonstrated by TPrxn experiments using C3H8 and C3H6 that a moderate oxygen ionic conductivity and a basic surface of the catalyst are needed for the selective conversion of propane to olefins.

CrOx/Ce1−xZrxO2 for chemical looping propane oxidative dehydrogenation: The redox interaction between CrOx and the support

Propane dehydrogenation is an attractive alternative for propylene production to petroleum-based routes. However, overcoming deactivation and toxicity of catalysts in propane direct dehydrogenation (PDH), and over oxidation in oxidative dehydrogenation (ODHP) remain challenging. Here, a chromium-based catalyst supported on a Ce-Zr solid solution is constructed for chemical looping oxidative propane dehydrogenation (CL-ODHP). A dual modulation of oxygen species by Zr doping was unraveled by characterizations and DFT calculation: the oxygen of surface CrOx was constrained while the oxygen mobility of the Ce-Zr support was promoted. Based on these properties, the interaction between surface CrOx and the support further enables an oxygen “donor–acceptor”, which potentially functions as in situ activation and regeneration of redox CrOx species as well as blockage of non-selective oxygen released from the Ce-Zr support. The optimized material (7.5Cr/Ce0.8Zr0.2O2) achieves propane conversion up to 50% and propylene yield of 31% at 600 °C, and has the lowest Cr content among previously reported Cr-based catalysts that have comparable performance. These results provide insights for the design of highly active and selective redox catalysts for chemical looping as a reaction engineering strategy for the upgrading of propane dehydrogenation processes.

Experimental study and kinetic modeling of methanol conversion to propylene with co-feeding of C4 and C5/C6 hydrocarbon cuts over a ZSM-5 catalyst.

Extensive experimental data were used to develop a comprehensive kinetic model for the methanol to propylene (MTP) process over a ZSM-5 catalyst. Preliminary experiments were performed to determine the reaction conditions that would ensure the absence of external (film) and internal mass transfer resistances. The kinetic experiments were subsequently carried out at 420-500 °C under conditions where mass transfer limitations were absent. A detailed reaction network was proposed for the MTP process based on the experimental product distribution and various reported kinetic models in the literature. According to the first series of experiments (without C4 and C5/C6 recycle streams) conducted at various temperatures, the best yield for propylene production was achieved at 480 °C with a water to methanol ratio of 0.7. Subsequently, kinetic experiments were performed at 480 °C and a water to methanol ratio of 0.7 using feeds with different amounts of C4 and C5/C6 hydrocarbons as recycle streams. Species material balances for the integral tubular reactor along with power-law rate functions and the Arrhenius equation for rate constants were employed in an optimization algorithm to obtain the kinetic parameters. The predictive ability of the model was checked against experimental data, and the kinetic parameters were validated by additional experiments.

Engineering the catalytic properties of CeO2 catalyst in HCl-assisted propane dehydrogenation by effective doping: A first-principles-based microkinetic simulation.

HCl-assisted propane dehydrogenation (PDH) is an attractive route for propene production with good selectivity. In this study, the doping of CeO2 with different transition metals, including V, Mn, Fe, Co, Ni, Pd, Pt, and Cu, in the presence of HCl was investigated for PDH. The dopants have a pronounced effect on the electronic structure of pristine ceria that significantly alters the catalytic capabilities. The calculations indicate the spontaneous dissociation of HCl on all surfaces with a facile abstraction of the first hydrogen atom except on V- and Mn-doped surfaces. The lowest energy barrier of 0.50 and 0.51eV was found for Pd- and Ni-doped CeO2 surfaces. The surface oxygen is responsible for hydrogen abstraction, and its activity is described by the p-band center. Microkinetics simulation is performed on all doped surfaces. The increase in the turnover frequency (TOF) is directly linked with the partial pressure of propane. The adsorption energy of reactants aligned with the observed performance. The reaction follows first-order kinetics to C3H8. Furthermore, on all surfaces, the formation of C3H7 is found as the rate-determining step confirmed by the degree of rate control (DRC) analysis. This study provides a decisive description of catalyst modification for HCl-assisted PDH.

Rational Construction of Ultrahigh Thermal Stable MOF for Efficient Separation of MTO Products and Natural Gas

Considering the important application foundation of propylene (C3H6) and ethylene (C2H4) production, as well as methane (CH4), in petrochemical industries, this report comprehensively investigated an innovative MOF material (Zn-BPZ-SA) that was synthesized by 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (H2BPZ) and squaric acid (H2SA) for separating methanol-to-olefins (MTO) products (C3H6/C2H4 mixtures) and natural gas (C3H8/C2H6/CH4 mixtures). Zn-BPZ-SA with great resistance toward water and exceptional thermal stability (520 °C), can preferentially adsorb C3H8 and C3H6 rather than C2H6 and C2H4, and in particular, reveals high C3H6 and C3H8 uptakes of 46.6 and 48.0 cm3 g–1 under the crucial low pressure (10 kPa, 298 K). The experimental and simulated transient breakthroughs for C3H6/C2H4 binary mixtures and C3H8/C2H6/CH4 ternary mixtures demonstrated that the MOF can separate these mixtures with long breakthrough time differences, yielding high-purity (>99.95%) products with high productivities: C2H4 (21.9–142.8 L kg–1) and CH4 (34.9–73.0 L kg–1). The excellent separation abilities can be attributed to the rich accessbile O/N and methyl binding sites scattered at the pore surfaces in framework.

Construction of Fluorinated Propane-Trap in Metal-Organic Frameworks for Record Polymer-Grade Propylene Production under High Humidity Conditions.

Propane/propene (C3 H8 /C3 H6 ) separation is essential in the petrochemical industry but challenging because of their similar physical and chemical properties. Adsorptive separation with C3 H8 -selective porous materials can energy-efficiently produce high-purity C3 H6 , which is highly promising for replacing conventional cryogenic distillation but suffers from unsatisfactory performance. Herein, through the precise incorporation of fluorinated functional groups into the confined pore space, a new fluorinated metal-organic framework(FDMOF-2) featuring the unique and strong C3 H8 -trap is successfully constructed. FDMOF-2 exhibits an unprecedented C3 H8 capture capacity of 140 cm3 cm-3 and excellent C3 H8 /C3 H6 (1:1, v/v) selectivity up to 2.18 (298 K and 1bar), thus setting new benchmarks for all reported porous materials. Single-crystal X-ray diffraction studies reveal that the tailored pore confinement in FDMOF-2 provides stronger and multiple attractive interactions with C3 H8 , enabling excellent binding affinities. Breakthrough experiments demonstrate that C3 H8 can be directly extracted from various C3 H8 /C3 H6 mixtures with FDMOF-2, affording an outstanding C3 H6 production (501mmol L-1 ) with over 99.99% purity. Benefiting from the robust framework and hydrophobic ligands, the separation performance of FDMOF-2 can be well maintained even under 70% relative humidity conditions.

Conceptual design and techno-economic analysis of a novel propane dehydrogenation process integrated with chemical looping combustion and CO2 hydrogenation

Propane dehydrogenation is a promising propylene production technology since it can alleviate its dependence on oil resources. However, the propane-to-propylene process will produce a large amount of hydrogen and hydrocarbons, which will not only waste energy, but also lead to CO2 emissions if they are directly burned for heating. In order to address these problems, this study proposes a novel propylene and methanol production process from propane, in which the hydrogen in the product gas is firstly extracted by pressure swing adsorption, then the remaining hydrocarbons are subjected to chemical looping combustion to provide heat and high purity CO2, and the hydrogen and CO2 are finally reacted into methanol. The exergy efficiency of the novel process is increased from 77.61% of the base process to 80.18% with about 98% of direct CO2 capture and about 40% of CO2 utilization. The fixed capital investment and total product cost & gross earnings cost of the novel process are 4200 million RMB and 3893 million RMB/y, 8.11% and 5.27% higher than those of the base process caused by additional costs of new units and power consumption, while its annual profit is 14 million RMB/y higher than the base process due to the extra methanol income. The study concludes that the novel process is superior in exergy efficiency and CO2 capture & utilization, but inferior in high capital investment.