Steam Cracking Of Ethane Research Articles

Effect of Reactor Alloy Composition on Coke Formation during Butane and Ethane Steam Cracking

Effect of Reactor Alloy Composition on Coke Formation during Butane and Ethane Steam Cracking

Numerical modeling of chemical looping oxidative dehydrogenation of ethane in parallel packed beds

Chemical looping oxidative dehydrogenation (CL-ODH) of ethane has the potential to be a highly efficient alternative to steam cracking for ethylene production. Accurate reactor modeling is of critical importance to efficiently scale up and optimize this new technology. This study reports a one-dimensional, heterogeneous packed bed model to simulate the CL-ODH of ethane to ethylene with a Na2MoO4-promoted CaTi0.1Mn0.9O3 redox catalyst. The overall reaction kinetics was well-described by coupling the gas-phase steam cracking of ethane with the reduction kinetics of the redox catalyst by H2 and C2H4. The impact of H2 on the formation rate of CO2 byproduct from C2H4 conversion was also thoroughly investigated to validate the applicability of the kinetic model under operational environments. The temperature variation within the different CL-ODH steps and the temperature distribution along the bed were also carefully considered. The accuracy of the model was validated by experiments conducted in a large lab-scale packed bed reactor (200 g catalyst loading), with an average deviation of 2.8% in terms of ethane conversion and ethylene yield. The model was subsequently used to optimize the operating parameters of the CL-ODH reactor, indicating that up to 63.7% single-pass C2 + olefin yield can be achieved with the current redox catalyst bed whereas further optimization of the redox catalyst to inhibit C2H4 activation can result in 69.4% single-pass C2 + yield while maintaining low CO2 selectivity.

Separation of ethylene and ethane using Co-Gallate pellets in a vacuum swing adsorption process

This work reports a vacuum swing adsorption (VSA) process that utilizes Co-gallate pellets to produce high-purity ethylene. The process is tested on two feed streams generated from the pyrolysis of naphtha and steam cracking of ethane, respectively. The VSA cycle consists of four steps: pressurization, adsorption, replacement with ethylene product and blowdown. A cyclic steady state (CSS) is reached for every test condition, verified by checking the profiles of column pressure, gas composition, and solid loading, which remain constant for ten subsequent cycles. Through analysis of the independent decision variables that affect the performance of the 80/20 (v/v) ethylene/ethane mixture separation, we identify desorption pressure and the replacement flowrate to feed flowrate ratio as the most significant factors. By optimizing these variables, we achieve an exceptional purity of 99.90% for ethylene with a 46.45% recovery and a productivity of 1.05 mol kg−1 per cycle. The Co-gallate adsorbent has a high affinity for ethylene and a low diffusion limitation, thus demonstrating superior potential for industrial ethylene/ethane separation compared to zeolite 4A and Ag+-Amberlyst 35.

The merit of pressure dependent kinetic modelling in steam cracking.

Renewable cracking feedstocks from plastic waste and the need for novel reactor designs related to electrification of steam crackers drives the development of accurate and fundamental kinetic models for this process, despite its large scale implementation for more than half a century. Pressure dependent kinetics have mostly been omitted in fundamental steam cracking models, while they are crucial in combustion models. Therefore, we have assessed the importance of pressure dependent kinetics for steam cracking via in-depth modelling and experimental studies. In particular we have studied the influence of considering fall-off on the product yields for ethane and propane steam cracking. A high-pressure limit fundamental kinetic model is generated, based on quantum chemical data and group additive values, and supplemented with literature values for pressure dependent kinetic parameters for β-scission reactions and homolytic bond scissions of C2 and C3 species. Model simulations with high-pressure limit rate coefficients and pressure dependent kinetics are compared to new experimental measurements. Steam cracking experiments for pure ethane and propane feeds are performed on a tubular bench-scale reactor at 0.17 MPa and temperatures ranging from 1058 to 1178 K. All important product species are identified using a comprehensive GC × GC-FID/q-MS. For homolytic bond scissions, the inclusion of pressure dependent kinetics has a significant effect on the conversion profile for ethane steam cracking. On the other hand, pressure dependence of C2 β-scissions significantly influences conversion and product species profiles for both ethane and propane steam cracking. The C3 β-scissions pressure dependence has a negligible effect in ethane steam cracking, while for propane steam cracking the effect is non-negligible on the product species profiles.

Pilot Test for the Purification and Utilisation of Process Water in Ethane Steam Cracking for Ethylene Production

Pilot Test for the Purification and Utilisation of Process Water in Ethane Steam Cracking for Ethylene Production

Electrochemically Engineered, Highly Energy-Efficient Conversion of Ethane to Ethylene and Hydrogen below 550 °C in a Protonic Ceramic Electrochemical Cell

Ethylene is one of the largest building blocks in the petrochemical industry, mainly produced by steam cracking of ethane derived from naphtha or shale gas at high temperatures (>800 °C). Despite its technical maturity and economic competitiveness, the thermal steam cracking of ethane is highly energy-intensive. Herein, an electrochemically engineered direct conversion process of ethane to produce hydrogen and ethylene using a planar protonic ceramic membrane reactor with a bi-functional three-dimensional catalytic electrode is reported, with a single-pass ethane conversion of 40% and ethylene yield of 26.7% at 550 °C. Compared with the industrial ethane steam cracking, this method saves process energy input by 45.1% and improves process energy efficiency by 50.6%, based on comprehensive process simulation using Aspen Plus software. Further, steam electrolysis treatment under the solid oxide electrolysis cell mode can regenerate the system’s catalytic performance and significantly alleviate catalytic degradation by 74%, demonstrating high techno-economic viability.

Productivity Enhancement for the Oxidative Coupling of Methane in Adiabatic Layered-Bed Reactors

Ethylene production via oxidative coupling of methane (OCM) in adiabatic packed-bed reactors is a promising route within the context of natural gas valorization. However, the high exothermicity of OCM imposes low inlet temperatures and, hence, low space-time yields. Layered-bed reactors are proposed in the present work as a potential alternative to mitigate this issue. In this modeling investigation, a first layer of active Sr/La2O3 catalyst is followed by a second layer of more selective NaMnW/SiO2 catalyst. Optimized bed compositions and operating conditions are shown to lead to up to a 10 times higher space-time yield compared to a single-catalyst bed. The achieved values of ca. 15 molC2+ s–1 mr–3 are comparable to conventional values from steam cracking of ethane, suggesting layered-bed adiabatic configurations as a promising way forward for intensified ethylene production via OCM.

Achieving high ethylene yield in non-oxidative ethane dehydrogenation

Steam cracking of ethane, a non-catalytic thermochemical process, remains the dominant means of ethylene production. The severe reaction conditions and energy expenditure involved in this process incentivize the search for alternative reaction pathways and reactor designs which maximize ethylene yield while minimizing cost and energy input. Herein, we report a comparison of catalytic and non-catalytic non-oxidative dehydrogenation of ethane. We achieve ethylene yields as high as 67 % with an open tube quartz reactor without the use of a catalyst at residence times ∼4 s. The open tube reactor design promotes simplicity, low cost, and negligible coke formation. Pristine quartz tubes were most effective, since coke formation was detected when defects were introduced by scratching the surface of the quartz. Surprisingly, the addition of solids to the quartz tube, such as quartz sand, alumina powder, or even Pt-based intermetallic catalysts, led to lower ethylene yield. Pt alloy catalysts are effective at lower temperatures, such as at 575 °C, but conversion is limited due to thermodynamic constraints. When operated at industrially relevant temperatures, such as 700 °C and above, these catalysts were not stable in our tests, causing ethylene yield to drop below that of the open tube. These results suggest that future research on non-oxidative dehydrogenation should be directed at optimizing reactor designs to improve the conversion of ethane to ethylene, since this approach shows promise for decentralized production of ethylene from natural gas deposits.

Experimental data supported techno-economic assessment of the oxidative dehydrogenation of ethane through chemical looping with oxygen uncoupling

Ethylene is an essential building block in the petrochemical industry and it is almost exclusively produced via ethane steam cracking, a well-established albeit highly energy and carbon dioxide intensive process. The oxidative dehydrogenation of ethane is a promising alternative to steam cracking reactions due to its exothermic nature, which decreases the overall energy requirements and carbon footprint. The need of a capital intensive air separation unit for producing oxygen limits its potential for industrial application. The current study investigates an alternative route, i.e. the production of oxygen via chemical looping, where oxygen is released in-situ by suitable oxygen carriers. The chemical looping oxidative dehydrogenation, supported by original experimental data, and the steam cracking processes are simulated with ASPEN Plus®. A comprehensive analysis of the energy requirements and an economic assessment are carried out for both processes. Compared with state-of-the-art ethane steam cracking, the proposed process provides ~28% energy savings per tonnes of ethylene produced and ~21% reduction in the resulting ethylene price. Sensitivity analysis show that the economy of the chemical looping oxidative dehydrogenation process is strongly sensitive to the feedstock price.

Olefina arinen ekoizpena: egungo egoera eta aurreikuspenak

Olefina arinak (bereziki, etilenoa eta propilenoa) industria petrokimikoko oinarrizko lehengaiak dira eta poliolefinak (polietilenoa eta polipropilenoa) ekoizteko erabiltzen dira nagusiki. Gaur egun, olefinen eskaria handituz doa: etilenoaren eskariak urteko % 3-5eko igoera izan du, eta propilenoak, aldiz, % 5-7koa. Etilenoaren eskaria bermatuta dago etanoaren ur-lurrun bidezko cracking termiko (SC) prozesuaren bitartez, baina propilenoaren eskaria betetzeko, ohiko prozesuek (SC eta cracking katalitikoa ohantze fluidizatuan (FCC)) eskaintzen duten hautakortasuna hobetu beharra dago. Gainera, industria-mailan ezarritako teknologiek erregai fosilen mendekotasun eta energia-kontsumo handia dute. Beraz, ohiko teknologiak hobetzea eta iturri berriztagarriak erabiltzen dituzten prozesuak garatzea dira gaur egungo findegiaren eta industria petrokimikoaren erronka nagusiak. Artikulu honetan, lehendabizi, olefina arinen erabilerak eta haien eskaria mundu-mailan aztertuko dira. Jarraian, ohiko teknologiak deskribatuko dira (iturri fosiletik abiatuz) eta, azkenik, bestelako teknologia berriztagarriak aurkeztuko dira, biomasaren eta hondakinen balorizazioan oinarritzen direnak.

Selective hydrogen combustion as an effective approach for intensified chemical production via the chemical looping strategy

Demand continues to grow rapidly for commodity chemicals, such as light olefins, at a time when the chemicals sector must strive to reduce its energy consumption and greenhouse gas emissions. Process intensification provides a framework for producing the same chemical products with higher efficiency and lower emissions. In recent years, chemical looping has received increasing attention as a strategy for intensified chemical production. For example, the chemical looping oxidative dehydrogenation (CL-ODH) of ethane to ethylene offers the potential for near order-of-magnitude reductions in process energy usage and CO2 emissions in comparison to conventional ethane steam cracking, while chemical looping dehydroaromatization (CL-DHA) of methane offers a pathway for aromatics production at higher yields. In these examples, the CL processes rely on selective hydrogen combustion (SHC) to remove the co-produced H2 gas as water, providing several benefits, including yield increase, autothermal operation, and simplified downstream separation. As a yield-enhancing strategy, SHC is not new. However, the design of redox catalysts for SHC in a chemical looping context has only recently begun to be explored. In this perspective, we summarize previous research on SHC in chemical production schemes, and we attempt to outline priority areas of research in the years to come.

Optimal design of ethylene and propylene coproduction plants with generalized disjunctive programming and state equipment network models

In this work, we propose a superstructure optimization approach for the optimal design of an ethylene and propylene coproduction plant. We formulate a superstructure that embeds ethane and propane steam cracking technologies, propane dehydrogenation and olefin metathesis processes. We represent the superstructure with a Generalized Disjunctive Programming model, and solve the problem through a custom implementation of the Logic-based Outer Approximation algorithm in GAMS. We propose a state-equipment-network representation to model potential distillation trains, as well as alternative acetylene reactor configurations. Rigorous models are formulated for distillation columns, compressors, turboexpanders, vessels and several process equipment units. The objective function is to maximize the net present value. We analyze four international price scenarios for raw material and utility costs, while considering global ethylene and propylene prices. We obtain the optimal scheme for each case. Numerical results show that the combination of ethane steam cracking, olefin metathesis and ethylene dimerization is the most profitable configuration under low ethane price scenarios, whereas the combination of ethane and propane steam cracking together with propane dehydrogenation is the optimal solution when the propane price is on the order of ethane price.

Electrochemistry Enhanced Activation of Ethane for Co-Production of Ethylene and Hydrogen with Low-Thermal-Budget and Low-CO2-Emission

The shale gas revolution and rapidly increasing demand for hydrogen (for upgrading lower-quality oils and automotive industry), have spurred the development of more energy-efficient and cost-effective approaches to convert natural gas/natural gas liquids into high value-added fuels and chemicals. Ethylene, one of the largest building blocks in petrochemical industry, is mainly manufactured from high temperature steam cracking of ethane or naphtha. This method is energy intensive and represents the single most energy consuming process in the chemical industry. To fully exploit the potential of ethane as feedstock, we demonstrated electrochemistry enhanced co-production of ethylene and hydrogen through non-oxidative dehydrogenation of ethane at temperatures below 600oC with close to theoretical ethane conversion rate and high ethylene yield. Significant reduction in energy consumption and CO2 emission, compared to the commercial ethane steam cracking process was achieved. The remarkable performance is enabled by advanced fabrication of solid oxide proton conducting electrochemical membrane reactors incorporated with highly selective electrocatalysts as well as comprehensive operation optimization.

Intensified Ethylene Production via Chemical Looping through an Exergetically Efficient Redox Scheme.

SummaryEthylene production via steam cracking of ethane and naphtha is one of the most energy and emission-intensive processes in the chemical industry. High operating temperatures, significant reaction endothermicity, and complex separations create hefty energy demands and result in substantial CO2 and NOx emissions. Meanwhile, decades of optimization have led to a thermally efficient, near-“perfect” process with ∼95% first law energy efficiency, leaving little room for further reduction in energy consumption and CO2 emissions. In this study, we demonstrate a transformational chemical looping–oxidative dehydrogenation (CL-ODH) process that offers 60%–87% emission reduction through exergy optimization. Through detailed exergy analyses, we show that CL-ODH leads to exergy savings of up to 58% in the upstream reactors and 26% in downstream separations. The feasibility of CL-ODH is supported by a robust redox catalyst that demonstrates stable activity and selectivity for over 1,400 redox cycles in a laboratory-scale fluidized bed reactor.

Evaluation of a Ti-Base Alloy as Steam Cracking Reactor Material.

Low-coking reactor material technologies are key for improving the performance and sustainability of steam crackers. In an attempt to appraise the coking performance of an alternative Ti–base alloy during ethane steam cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe–Ni–Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti–base alloy, however, its coking performance was significantly worse compared to the typically used Fe–Ni–Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti–base alloy cannot be considered an industrially noteworthy steam cracking reactor alloy.

Ethane Steam Cracking Inferential Model Development using Artificial Neural Network

Abstract During normal operation, the product yield distribution of ethane steam cracking is obtained using analyzers and lab sampling to measure the cracking severity. Since analyzers take time to produce result, primarily depending on analyzers and lab testing to determine main product yield will hinder immediate control action to the process. In this study, data generated from ASPEN Plus Dynamics is used as feed data to develop the inferential model for product yield prediction based on real time operating parameters. The finalized model is a 4x2 ANN model, with 10 hidden nodes. Mean Squared Error (MSE) analysis shows that the model can accurately predict ethane and ethylene yields of the process, with MSE of 2.78x10-5 and 3.41x10-6, respectively. On top of that, R-squared analysis shows goodness-of-fit of 99.4% and 98.4%, respectively.

Sustainable Design and Synthesis of Shale Gas Processing and Chemical Manufacturing Processes

In this work, we propose a superstructure of integrated shale gas processing and chemical manufacturing processes with 51,840 alternative possible process designs. The superstructure consists of eight sections, namely acid gas removal, dehydration, NGLs recovery, NGLs separation, hydrocarbons conversion, light olefins separation, C4 separation, and acid gas disposal. For the steam cracking reactions in the hydrocarbons conversion section, we optimize the product distributions of steam cracking of ethane, propane, n-butane, and i-butane. Extensive process simulations are performed for all the involved processes in the superstructure in order to collect high-fidelity process data and develop detailed process models for the technology/process alternatives in the superstructure. Next, we propose a multiobjective mixed-integer nonlinear programming (MINLP) superstructure optimization model with five groups of constraints, namely superstructure network configuration constraints, mass balance constraints, energy balance constraints, techno-economic evaluation constraints, environmental impact assessment constraints. Three objective functions are maximizing the net present value per GJ of raw shale gas, minimizing the global warming potential per GJ of raw shale gas, and minimizing the water footprint per GJ of raw shale gas, respectively. A tailored global optimization algorithm is applied to efficiently solve the resulting nonconvex MINLP problem. The application of the proposed framework is illustrated through a case study based on a Marcellus shale gas feed.

Inhibition effect of CeO2 promoted SiO2 coating on coke growth during steam cracking of ethane

The main goal of this research is to develop an effective coating to inhibit the direct contact of hydrocarbon with reactor metal wall along with the catalytic conversion of coke to carbon oxides. For this purpose, CeO2 promoted SiO2 coatings were deposited on the surface of an industrial HP 40 alloy. With the purpose of obtaining an effective passive coating with an appropriate morphology and low defects, different synthesis parameters such as the pretreatment of sublayer with sodium carbonate and sulfuric acid solutions and the roughness of HP 40 coupon is investigated. Afterwards, the SiO2 coating was improved with cerium oxide using different Ce/Si molar ratios (0, 0.25, 0.5, 0.75 and ∞) according to characterization and ethane cracking results. The amount of deposited coke is reduced with increasing the Ce/Si molar ratio up to 0.75. The coke is reduced from 1.6mg for blank HP 40 to about 0.5 and 0.6mg for 0.75CeO2/SiO2/HP40 and CeO2/SiO2/HP40 specimens, respectively. In addition, the characterization results of coked samples after ethane cracking revealed that the coating of different optimal layers successively inhibited the formation of filamentous carbon and metal migration. Thus, the deposited coke on the optimal coating coupons is mostly composed of amorphous soft carbon.

Co-Production of Ethylene and Hydrogen Via Non-Oxidative Dehydrogenation of Ethane Below 400oc

Ethylene, a major intermediate in manufacture of polymers and petrochemicals, is conventionally produced by energy intensive high temperature (higher than 800oC) steam cracking of ethane. By using a proton-conducting solid oxide cell (SOC), ethylene and pure hydrogen can be co-produced at a much lower temperature via electrochemical dehydrogenation. In this paper, we report high efficient co-production of hydrogen and ethylene on a proton-conducting Ni-BaZr0.1Ce0.7Y0.2–xYbxO3-δ (BZCYYb) hydrogen electrode supported SOC below 400oC. The SOC presents high Faraday efficiency as well as an ethylene selectivity close to 100%. Our approach decreases the processing energy demand dramatically with no CO2 emission when compared with the traditional ethane steam cracking process. The low temperature electrochemical dehydrogenation process in this study provides a promising prospective for next-generation petrochemical manufacturing, shifting the paradigm from thermal chemical practice to energy-saving and eco-friendly regime.

Role of Presulfidation and H2S Cofeeding on Carbon Formation on SS304 Alloy during the Ethane–Steam Cracking Process at 700 °C

The influence of presulfidation and H2S cofeeding on the carbon formation on SS304 alloy in the ethane–steam cracker was investigated in a laboratory-scale quartz reactor setup. SS304H coupons and SS304L powder samples were exposed to ethane–steam and dry ethane in varying H2S content (0–50 ppm), and the SS304 samples were characterized by scanning electron microscopy. This study shows that H2S cofeeding decreases catalytic carbon formation; while it increases the pyrolytic carbon formation during ethane–steam cracking. Preoxidation, presulfidation, and addition of steam to ethane feed also reduces the amount of catalytic carbon formed on the SS304H surface in short-term experiments (4 h). Presulfidation and addition of H2S to ethane feed significantly influences the shape and size of the carbon formed on the surfaces of investigated metal alloys. Presulfidation and H2S cofeeding reduced spalling of the SS304H coupon surface during coking/decoking and thermal cycling.