Propylene Production Research Articles

Emergency shutdowns of propylene production plants: Root cause analysis and availability modeling

Unplanned shutdown events in chemical process plants cause revenue losses due to production curtailments, repair costs, and harmful environmental and safety effects on plant personnel and the surrounding community. Several recent studies have used news articles and databases to perform statistical analyses and modeling of the causes and consequences of chemical process accidents, but these studies do not analyze the operating deviations that led to shutdowns. This work structures narratives about unplanned shutdown events into data, analyzes the causes of those events, and uses the collected data to model the failure probability of process plants. A case study comparing two propylene production technologies, steam cracking and propane dehydrogenation is developed. We use a set of 118 shutdown events reported in four sources across a five-year span for 7 propylene production plants. Using this data, the three leading causes for unplanned shutdowns in both propylene production technologies were determined to be: equipment trips/shutdowns, utility supply interruptions, and weather-related events. A power law process (PLP) for data from multiple repairable systems is used to model the failure behavior for both technologies. For the data collected, this procedure indicated an increasing failure intensity function for both technologies, with propane dehydrogenation increasing more significantly. In addition, both maximum likelihood estimates (MLEs) and confidence intervals for the PLP parameters are presented. Since these are repairable systems, an estimated inherent availability is determined for both technologies. Finally, recommendations that address how to reduce the occurrence of these events and mitigate their consequences are discussed.

A kinetic investigation on low-temperature ignition of propane with ozone addition in an RCM

To extend the temperature for propane ignition to a lower region (< 680 K), ozone (O3) was used as an ignition promoter to investigate the low-temperature chemistry of propane. Ignition delay times for propane containing varying concentrations of O3 (0, 100, and 1000 ppm) were measured at 25 bar, 654–882 K, and equivalence ratios of 0.5 and 1.0 in a rapid compression machine (RCM). Species profiles during propane ignition with varying O3 concentrations were recorded using a fast sampling system combined with a gas chromatograph (GC). A kinetic model for propane ignition with O3 was developed. O3 shortened ignition delay times of propane significantly, and the NTC behavior was weakened. O atoms released from O3 reacted with propane through hydrogen abstraction reactions, which led to the fast production of OH radicals. The following oxidation of fuel radicals generated additional OH radicals. Consequently, the inhibition caused by the slow chemistry of hydrogen peroxide (H2O2) in the NTC region was weakened in the presence of O3. Experimental results with O3 addition can provide extra constraints on the low-temperature chemistry of propane. Species profiles during propane ignition at 730 K with 1000 ppm O3 addition showed the production of propanal (C2H5CHO), acetone (CH3COCH3), and acetaldehyde (CH3CHO) was promoted significantly. Model analyses indicated that O3 shifted the oxidation temperature of propane to a lower region, in which reactions of ROO radicals (NC3H7O2 and IC3H7O2) tend to generate RO radicals (NC3H7O and IC3H7O). The promotion of RO radicals led to the fast production of C2H5CHO, CH3COCH3, and CH3CHO. The corresponding species profile highlighted the reaction relevant to ROO and RO radicals (NC3H7O + O2 = C2H5CHO + HO2 and 2 IC3H7O2 = 2 IC3H7O + O2). Rate constants of these reactions were updated, which can potentially improve the performance of the core mechanism under lower temperatures and provide references for model development of larger hydrocarbons.

Revealing the Catalytic Role of Sn Dopant in CO2‐Oxidative Dehydrogenation of Propane over Pt/Sn‐CeO2 Catalyst

AbstractCO2‐oxidative dehydrogenation of propane (CO2‐ODHP) provides a promising route for propylene production. Sufficient propane conversion and propylene selectivity remain a great challenge due to the difficulty in activating inert propane and CO2 simultaneously. Herein, a Sn doped CeO2 supported Pt (Pt/Sn‐CeO2) catalyst in CO2‐ODHP reaction is reported. Sn doping appears to kill two birds with one stone for propane and CO2 activation. On the one side, it increases the electron density of Pt species via PtSn alloy formation, promoting propane adsorption and C−H bond cleavage. On the other side, it enhances oxygen vacancy concentrations of CeO2 support, facilitating CO2 dissociation. A higher propylene selectivity (63.9 % vs 22.3 %) was obtained on 0.1 wt % Pt/1.0 wt % Sn‐CeO2 than that on 0.1 wt % Pt/CeO2 with a comparable propane conversion (15.1 % vs 14.3 %) at 550 °C after 240 min on stream. This work provides a reference for designing efficient catalysts.

Adsorption-Enhanced Bifunctional Catalysts for In Situ CO2 Capture and Utilization in Propylene Production: A Proof-Of-Concept Study

Adsorption-Enhanced Bifunctional Catalysts for In Situ CO₂ Capture and Utilization in Propylene Production: A Proof-Of-Concept Study

Bulk and intramolecular carbon isotopic compositions of hydrocarbon gases from laboratory pyrolysis of oil shale of the Green River Formation: Implications for isotope structures of kerogens

Evaluation of intramolecular isotope distributions within organic compounds can provide important insights into gas formation processes and structural properties of gas-generating precursors, such as kerogen, bitumen, and oil, in natural reservoirs. Until recently, little has been known about the intramolecular isotope distributions within kerogens. In this study, we conducted systematic pyrolysis experiments of gas generation from a lacustrine oil shale of the Eocene Green River Formation under hydrous and anhydrous conditions (equivalent maturity or Easy %Ro: 0.76 to 3.27 at 310 to 480 °C for 3 to 50 days), measuring gas yields and compositions, as well as bulk and position-specific (PS) carbon isotope compositions. Gas generation processes were investigated in combination with kinetic Monte Carlo (kMC) simulations on a model Type I kerogen based on the chemical structures of oil shale of the Green River Formation. The comparison of our experimental results with kMC modelling indicates a series of β-scission, radical isomerization, and recombination reactions better represent the bulk isotope compositions of propane in the pyrolysis of the oil shale of the Green River Formation, but the ΔCc-t (= δ13Ccen – δ13Cter) values of propane at Easy %Ro > 1.5 can be better simulated by a simple combination of propyl groups with H radicals. Combining our previous works on marine shale of the Woodford Formation and Springfield Coal Member of the Carbondale Formation, PS carbon isotopes of propane indicate that in the lacustrine shales of the Green River Formation and the marine Woodford Shale, propane is sourced from CC bond cleavage, while CO bond cracking generates propane from coal at the initial kerogen cracking stage. At high maturity, the differences of late-stage propane production among the source rocks lead to the different bulk and PS C kinetic isotope effects of propane. Our findings suggest that the δ13C at the terminal position of propane precursors is likely up to 3.6‰ higher than at the central position in the Green River kerogen, while they are similar in the marine shale of Woodford Formation. In addition, the δ13C at the central position of propyl groups attached to heteroatom compounds is relatively more positive in the Springfield Coal Member of the Carbondale Formation than in Green River kerogen. A comparison of intramolecular C isotopes of propyl groups in the kerogens with their bulk δ13C, based on the PS δ13C of early-generated propane, contributes to our understanding of heterogeneities of isotopic structures of sedimentary organic matter.

Low temperature catalytic conversion of CH4, CO2, and C2H4 to value-added C3 oxygenates and olefins via C1-C2 coupling on Pd-Au/CeO2

The catalytic conversion of CH4 and CO2 in the presence of more reactive co-reactants C2H4 and O2 on Pd-Au/CeO2 is achieved at 200 °C and elevated pressures. Propene and acetone were produced from the catalyzed reaction of CH4 +C2H4 +O2; addition of CO2 to the reactant stream produced methyl acetate (MAc) but it significantly reduced the C-selectivities of propene and acetone. DRIFTS experiments confirmed the formation of methoxy species from CH4 +CO2 at 200 °C, which is an intermediate in the formation of MAc. Control experiments with blanks, and with CeO2 did not show any propene, acetone, or MAc products. The complete oxidation of C2H4 was avoided; the catalyst is stable, and reactant conversions and product yields were sustained for the observed 1200 min time-on-stream, indicating that there is little or no carbon deposition and sintering. This direct coupling of CH4 and C2H4 intermediates to higher carbon-number products at 200 °C is significant.

Photocatalytic Oxidative Dehydrogenation of Propane for Selective Propene Production with TiO2.

Oxidative dehydrogenation of propane (ODHP) as an exothermic process is a promising method to produce propene (C3H6) with lower energy consumption in chemical industry. However, the selectivity of the C3H6 product is always poor because of overoxidation. Herein, the ODHP reaction into C3H6 on a model rutile(R)-TiO2(110) surface at low temperature via photocatalysis has been realized successfully. The results illustrate that photocatalytic oxidative dehydrogenation of propane (C3H8) into C3H6 can occur efficiently on R-TiO2(110) at 90 K via a stepwise manner, in which the initial C-H cleavage occurs via the hole coupled C-H bond cleavage pathway followed by a radical mediated C-H cleavage to the C3H6 product. An exceptional selectivity of ∼90% for C3H6 production is achieved at about 13% propane conversion. The mechanistic model constructed in this study not only advances our understanding of C-H bond activation but also provides a new pathway for highly selective ODHP into C3H6 under mild conditions.

Biogenic propane production by a marine Photobacterium strain isolated from the Western English Channel.

Propane is a major component of liquefied petroleum gas, a major energy source for off-grid communities and industry. The replacement of fossil fuel-derived propane with more sustainably derived propane is of industrial interest. One potential production route is through microbial fermentation. Here we report, for the first time, the isolation of a marine bacterium from sediment capable of natural propane biosynthesis. Propane production, both in mixed microbial cultures generated from marine sediment and in bacterial monocultures was detected and quantified by gas chromatography-flame ionization detection. Using DNA sequencing of multiple reference genes, the bacterium was shown to belong to the genus Photobacterium. We postulate that propane biosynthesis is achieved through inorganic carbonate assimilation systems. The discovery of this strain may facilitate synthetic biology routes for industrial scale production of propane via microbial fermentation.

Potassium-promoted Pt–In bimetallic clusters encapsulated in silicalite-1 zeolite for efficient propane dehydrogenation

Propane dehydrogenation (PDH) has been a promising method to satisfy the increasing demand for propylene, but Pt-based catalysts always suffer from sintering and coke formation. Developing stable and efficient catalysts for PDH is of great significance for the industry. Herein, the paper reports that a catalyst with potassium-promoted Pt-In bimetallic clusters encapsulated in silicalite-1 (S-1) zeolite works as an efficient and stable catalyst for PDH. The catalyst achieves a propane conversion of 43.73 % with 97.14 % selectivity of propene and an extremely high propylene productivity of 20.33 mol gPt-1h-1 with a weight hourly space velocity (WHSV) of 6.75 h−1. No obvious deactivation occurs after 48 h on stream, affording an extremely low deactivation constant of 0.0025 h−1. The introduction of indium species greatly improves the propene selectivity and restricts the coke formation. The introduction of K+ into S-1 can significantly enhance the catalytic activity and the stability of the catalyst. The catalyst with excellent activity and stability is potential for industrial application.

Facile Fabrication of α-Alumina Hollow Fiber-Supported ZIF-8 Membrane Module and Impurity Effects on Propylene Separation Performance.

The separation of C3 olefin and paraffin, which is essential for the production of propylene, can be facilitated by the ZIF-8 membrane. However, the commercial application of the membrane has not yet been achieved because the fabrication process does not meet industrial regulatory criteria. In this work, we provide a straightforward and cost-effective membrane fabrication technique that permits the rapid synthesis of ZIF-8 hollow fiber membranes. The scalability of the technology was confirmed by the incorporation of three ZIF-8 hollow fiber membranes into a single module using an introduced fiber mounting methodology. The molecular sieving characteristics of the ZIF-8 membrane module on a binary combination of C3 olefin and paraffin (C3H6/C3H8 selectivity of 110 and a C3H6 permeance of 13 GPU) were examined at atmospheric conditions. In addition, the high-pressure performance of these membranes was demonstrated at a 5 bar of equimolar binary feed pressure with a C3H6/C3H8 selectivity of 55 and a C3H6 permeance of 9 GPU due to propylene adsorption site saturation. To further accurately portray the separation performance of the membrane on an actual industrial feed, the effect of impurities (ethylene, ethane, butylene, i-butane, and n-butane), which can be found in C3 splitters, was investigated and a considerable decrement (~15%) in the propylene permeance upon an interaction with C4 hydrocarbons was confirmed. Finally, the long-term stability of the ZIF-8 membrane was confirmed by continuous operation for almost a month without any loss of its initial performance (C3H6/C3H8 separation factor of 110 and a C3H6 permeance of 13 GPU). From an industrial point of view, this straightforward technique could offer a number of merits such as a short synthesis time, minimal chemical requirements, and excellent reproductivity.

Experimental Study of the Impact of Trace Amounts of Acetylene and Methylacetylene on the Synthesis, Mechanical and Thermal Properties of Polypropylene.

During the production of polymer-grade propylene, different processes are used to purify this compound and ensure that it is of the highest quality. However, some impurities such as acetylene and methyl acetylene are difficult to remove, and some of these impurities may be present in the propylene used to obtain polypropylene, which may have repercussions on the process. This study evaluates the impact of these acetylene and methyl acetylene impurities on the productivity of the polypropylene synthesis process and on the mechanical and thermal properties of the material obtained through the synthesis of eight samples with different concentrations of acetylene and eight samples with different concentrations of acetylene. We discovered that for the first concentrations of both acetylene (2 and 3 ppm) and methyl acetylene (0.03 and 0.1), the MFI, thermal recording, and mechanical properties of the resin were unaffected by the variation of the fluidity index, thermal degradation by TGA, and mechanical properties such as resistance to tension, bending, and impact. However, when the concentration exceeded 14 ppm for methyl acetylene and 12 ppm for acetylene, the resistance of this resin began to decrease linearly. Regarding production, this was affected by the first traces of acetylene and methyl acetylene progressively decreasing.

Environmental Impact Assessment of Asaluyeh Gas Refinery Products Based on Blue Water Footprint Measurement

Background: The current state of water resources in Iran and the process of governing them in recent years indicate the importance of demand management and water consumption reduction in all fields, such as agriculture, industry, service, and domestic. Suppose water consumption reduction or demand management are not applied, or accurate knowledge of freshwater consumption assessment is not acquired in various environmental fields due to dwindling water resources. In that case, it will be difficult or uneconomical for industrial production to provide fresh water in the near future. Furthermore, the adverse environmental impact of freshwater consumption on various industries and its recurrence will inevitably cause an imbalance in the ecosystem and result in many problems. Methods: This study analyzed eight parameters of environmental impact assessment through Life Cycle Assessment (LCA) after apprising blue water footprints in the production of methane, ethane, propane, butane, gas condensate, and sulfur at the processing units of Asalouyeh Gas Refinery by taking the essential items into account (consumed blue water, electricity consumption, and consumption of common and widely used chemicals in the production process). Results: The results of the environmental impact assessment of producing each ton of the aforementioned products are as follows: Environmental impact of acidification: The greatest impact was left by gas condensate, which produced 5.086 kg of SO2, whereas the smallest impact was made by sulfur production with 0.813 kg. Environmental impact of eutrophication: The greatest impact with 0.476 kg of PO4-- was left by methane production, whereas the smallest impact was made by sulfur production with 0.147kg of PO4--. Environmental impact of global warming: The greatest impact was made by gas condensate, which produced 1140.161 kg of CO2, whereas the smallest impact was made by sulfur production, which produced 182.425 kg. Environmental impact of photochemical oxidation: The greatest impact was left by gas condensate, which produced 4.313kg of NMVOC, whereas the smallest impact was made by sulfur production, which produced 0.69 kg of NMVOC. Environmental impact of abiotic element depletion: This parameter is considered because of the very small quantities of software in all gas refinery products. Environmental impact of fossil fuel depletion: The greatest impact was left by gas condensate, which produced 85137.066 kg of MJ, whereas the smallest impact was made by sulfur production, which produced 13621.928 kg of MJ. Environmental impact of water scarcity: The greatest impact was left by gas condensate with 15906.544 m3, whereas the smallest impact was left by sulfur production with 2545.046 m3. Environmental impact of ozone layer depletion: The greatest impact was made by sulfur, which produced 8.121 kg of CFC11, whereas the smallest environmental impact, with a large difference from sulfur and a small difference in numerical values, was left by other refinery products. Conclusions: The results of measuring the blue water footprints in the production process revealed that gas condensate consumed the largest amount of water and sulfur consumed the smallest.

Economic Analysis of Separation Unit of Methanol to Propylene Production Based on Optimization of Refrigeration Cycles Using Pinch and Exergy Analysis

In this study, optimization and economic analysis of the separation of light gases in the methanol to propylene, MTP, process along with refrigeration cycles design are performed, by using pinch and exergy analysis. In the course of the separation process optimization and refrigeration cycles design, by using a Visual Basic, VB, program and genetic algorithm, GA, rigorous distillation simulation is carried out, then streams information is employed to find optimum temperature levels, corresponding to tower condenser temperature, by minimizing the areas between the Exergy Grand Composite Curve, EGCC, and constant temperature levels of refrigeration cycles. Economic calculations were performed to obtain the lowest total annual cost, TAC, for refrigeration cycles, towers and other equipment. Two cases of the direct and indirect sequences are examined through the developed framework, inspection of their results represents that the operational cost has a significant contribution to the TAC. As a result, heat integration would reduce it by nearly 60%. Also, scrutinized analysis of the optimization results, especially by considering the TAC and its contributions, for the direct and indirect sequences, leads to the conclusion that indirect sequence would exhibit lower cost for light gas separation. The framework represented herein paves a way to the systematic design of integrated low-temperature separation processes with refrigeration cycles.

Catalytic deconstruction of waste polyethylene with ethylene to form propylene.

The conversion of polyolefins to monomers would create a valuable carbon feedstock from the largest fraction of waste plastic. However, breakdown of the main chains in these polymers requires the cleavage of carbon-carbon bonds that tend to resist selective chemical transformations. Here, we report the production of propylene by partial dehydrogenation of polyethylene and tandem isomerizing ethenolysis of the desaturated chain. Dehydrogenation of high-density polyethylene with either an iridium-pincer complex or platinum/zinc supported on silica as catalysts yielded dehydrogenated material containing up to 3.2% internal olefins; the combination of a second-generation Hoveyda-Grubbs metathesis catalyst and [PdP(tBu)3(μ-Br)]2 as an isomerization catalyst selectively degraded this unsaturated polymer to propylene in yields exceeding 80%. These results show promise for the application of mild catalysis to deconstruct otherwise stable polyolefins.

Promotion Effect of Gold on Mo/ZSM-5 Catalyst for the Catalytic Cracking of Light Diesel Oil to Increase Propylene Production

Promotion Effect of Gold on Mo/ZSM-5 Catalyst for the Catalytic Cracking of Light Diesel Oil to Increase Propylene Production

Low-temperature propane oxidative dehydrogenation over UiO-66 supported vanadia catalysts: Role of support confinement effects

Overoxidation is the principal barrier against commercializing propane oxidative dehydrogenation (PODH) catalysts for propylene production. The current approach to reducing overoxidation, i.e., coating the non-selective support surface with a monolayer of active phase, can itself increase the probability of overoxidation of the produced propylene due to polymerization of active phase species. Incorporating the “confinement agents” onto the metal oxide support might be considered as an alternative solution to prevent hydrocarbons from reaching the support and overoxidizing. Herein, the UiO-66 metal–organic framework, which contains numerous organic ligands connected to the zirconia nodes, was used as support for the vanadia active phase to highlight the role of support's confinement effects on the overall catalytic performance toward the PODH. The UiO-66 supported vanadia catalysts with various vanadium loadings were fabricated via an ultrasonic-assisted wet impregnation procedure. The catalytic function is related to the underlying chemical processes at catalyst surfaces using physicochemical characterization techniques, PODH performance measurements, and machine learning tools. The results showed that the catalyst with a relatively low vanadia density of 2.7 nm−2, equivalent to less than half of the entire support surface coverage, could achieve propylene productivity of 4.43 gC3H6gcat-1h-1, propane conversion of 17.1%, and propylene selectivity of 49.7% at 350 °C.

Mechanistic Interpretations and Insights for the Oxidative Dehydrogenation of Propane via CO2 over Cr2O3/Al2O3 Catalysts

Oxidative dehydrogenation (ODH) of alkanes using carbon dioxide as a soft oxidant has recently emerged as a potentially attractive alternative to steam cracking for the production of light olefins. To elucidate reaction pathways and their dependence on the operating conditions, CO2-assisted propane dehydrogenation over a redox-active Cr2O3/Al2O3 catalyst was examined in a packed bed reactor as a function of temperature, Cr2O3/CO2 feed ratio, and residence time. Previous ODH studies have largely focused on CO2-rich conditions with the aim of preventing coke formation. However, at T = 600 °C the present study finds that the use of propane-rich conditions (1 ≤ C3H8/CO2 ≤ 2.5) maximizes propylene production and selectivity while maintaining catalyst stability. It is postulated that the selective Mars van Krevelen dehydrogenation process is optimized at these ratios. Excess CO2 apparently promotes nonselective dehydrogenation and dry reforming pathways that generate additional CO, adversely impacting catalyst stability via the Bouduard reaction. This hypothesis is supported by complementary investigations of the reverse water gas shift reaction and thermodynamic analysis. The findings and methodology presented here are likely applicable to related ODH processes with other alkanes and redox-active catalysts.

Adsorption, thermal conversion, and catalytic hydrogenation of acrolein on Cu surfaces

The adsorption, thermal chemistry, and catalytic hydrogenation of acrolein on copper model surfaces was characterized by a combination of surface-science techniques, namely, reflection–absorption infrared spectroscopy (RAIRS) and temperature program desorption (TPD), quantum mechanics (DFT) calculations, and catalytic kinetic measurements using a so-called “high-pressure cell”. Adsorption of acrolein on the Cu surface was found to involve both the carbonyl oxygen atom and the CC bond. Thermal activation leads to early dissociation and dehydrogenation to produce acetylene and carbon monoxide below 160 K, and later to the production of ketene (220 K) and propene (260 K). Under vacuum hydrogenation with H2 is not possible, but upon predosing of the surface with atomic H all the possible hydrogenation products, namely, propanal, 1-propanol, and allyl alcohol, were detected in TPD experiments, at 162, 190, and 210 K, respectively. Finally, catalytic hydrogenation under atmospheric pressures is slow and only produces propanal, at turnover frequencies below 0.2 s−1.

Ultramicroporous Hydrogen-Bonded Organic Framework Material with a Thermoregulatory Gating Effect for Record Propylene Separation.

Propane/propylene separation is one of the most challenging and energy-consuming but most important tasks in the petrochemical industry. Herein, a stable hydrogen-bonded organic framework (HOF-FJU-1) was tailor-made for highly efficient propylene separation from binary C3H6/C3H8 and even seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 mixtures. The temperature-controllable diffusion channels in HOF-FJU-1 have enabled the porous material to completely exclude propane to reach high-performance propylene purification under energy-efficient operation conditions. Single-crystal structural analysis revealed that the well-matched pore aperture of HOF-FJU-1 can exactly accommodate propylene molecules via multiple intermolecular interactions, exhibiting a very high propylene/propane selectivity of 616 at 333 K. The propylene purity and productivity are over 99.5% and 30.2 L kg-1 from the binary C3H6/C3H8 (50/50) mixture at 333 K. Through a follow-up column separation of C3H6/C2H4 at 353 K, not only high-purity propylene (99.5%) but also ethylene (98.3%) can be readily collected from the seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 (31/10/25/10/10/1/13) cracking gas mixtures. The great potential of HOF-FJU-1 for the industrial propylene separation process has been further supported by the high stability of this porous material under different environments and straightforward processibility and regeneration feasibility.

High-entropy intermetallics on ceria as efficient catalysts for the oxidative dehydrogenation of propane using CO2

The oxidative dehydrogenation of propane using CO2 (CO2-ODP) is a promising technique for high-yield propylene production and CO2 utilization. The development of a highly efficient catalyst for CO2-ODP is of great interest and benefit to the chemical industry as well as net zero emissions. Here, we report a unique catalyst material and design concept based on high-entropy intermetallics for this challenging chemistry. A senary (PtCoNi)(SnInGa) catalyst supported on CeO2 with a PtSn intermetallic structure exhibits a considerably higher catalytic activity, C3H6 selectivity, long-term stability, and CO2 utilization efficiency at 600 °C than previously reported. Multi-metallization of the Pt and Sn sites by Co/Ni and In/Ga, respectively, greatly enhances propylene selectivity, CO2 activation ability, thermal stability, and regenerable ability. The results obtained in this study can promote carbon-neutralization of industrial processes for light alkane conversion.