Learn How Advanced PDH Technologies are Paving the Way for Greener Propylene Production

18 Jan 2024

Propylene is an important building block in the production of a wide range of plastics, chemicals, and fuels. However, traditional propylene production methods rely on non-renewable fossil fuels, resulting in high greenhouse gas emissions and environmental impacts. 

Advanced propane dehydrogenation (PDH) technologies have emerged as a promising solution to enable sustainable and low-carbon propylene production. For instance, catalysts used in PDH, such as Chromia and Platinum-tin, have been developed to increase yield, reduce coke formation, and extend catalyst lifespan. 

By utilizing propane, a readily available and low-cost feedstock, PDH technologies can produce propylene with significantly lower emissions and energy consumption compared to traditional methods. 

Moreover, the integration of advanced separation techniques, such as membrane technology and adsorption, has helped in the efficient separation of propylene from other products, leading to increased purity. 

This article will explore the latest advancements in PDH technologies and their potential to pave the way for a more sustainable and resilient propylene industry. 

1. CATOFIN Technology 

The CATOFIN technology is a proprietary process developed by Lummus Technology, a key licenser of exclusive technologies for petrochemicals, refining, gasification, and gas processing, based in Houston, Texas. CATOFIN technology has been developed for the production of olefins, such as propylene and iso-butylene, from paraffin-based feedstocks. 

CATOFIN technology uses a catalyst produced by Clariant, a Swiss company specializing in the development of process catalysts. The company produces customized catalysts designed specifically for on-purpose propylene production. 

Moreover, to add to the innovative CATOFIN technology, Clariant has developed a new metal-oxide, known as Heat Generating Material (HGM), which is customized to enhance selectivity and yield in Catofin units as well as to reduce emissions. HGM is integrated into the catalyst bed, where it undergoes oxidation and reduction during the operation cycle, generating heat and facilitating the dehydrogenation reaction. 

The CATOFIN process occurs in superior thermodynamic operating conditions, which include vacuum and lower temperature for reactors. These operating conditions result in high conversion and selectivity for converting paraffins to olefins. Even when co-producing propylene and isobutylene, high conversions can be maintained. 

The CATOFIN process uses a single stage of reaction, providing reliable and robust operation, high on-stream factor, and the highest per-pass conversion and selectivity. The process also has the lowest raw material consumption and is flexible with regard to feeding purity, requiring no feed pretreatment. It provides a higher hydrogen yield and a quicker time to start up and make products. 

 The CATOFIN process has a simple carbon steel (CS) metallurgy for reactors, and there is no need for proprietary equipment, catalyst makeup, or chlorine handling/caustic scrubbing. The process also does not require hydrogen recycling or dilution steam. 

Presently, nine propane dehydrogenation plants and six iso-butane dehydrogenation plants utilize CATOFIN technology worldwide to manufacture over 5.0 million tons of propylene and nearly 3.0 million tons of iso-butylene annually. 

The simplicity and reliability of the process make it a popular choice for propylene production, contributing significantly to the chemical industry's growth and development. 

2. Catalytic Non-Thermal Plasma (CNTP) Technology 

Susteon, initially a startup based in India, is now a global provider of energy solutions for net zero emissions based in North Carolina, U.S. With the help of its project partners, North Carolina State University, New Castle University, and Southern California Gas Company (SoCalGas), Susteon has developed a new catalytic non-thermal plasma (CNTP) technology in response to the pressing need for more sustainable and environment-friendly methods of ethylene and propylene production. 

The current steam cracking process, which relies on naphtha as the feedstock, emits large amounts of CO2, producing approximately 2.5 tons of CO2 per ton of olefin. Globally, the annual CO2 emissions from the production of ethylene and propylene amount to around one billion tons. 

In contrast, the CNTP technology developed by Susteon employs CO2 as a gentle oxidant for the creation of ethylene and propylene from ethane and propane, respectively. 

The crucial step in the process is the plasma-assisted catalytic conversion of carbon dioxide to carbon monoxide and oxygen radicals at low temperatures. The oxygen radicals then react with ethane or propane, breaking down the C-H bonds to form ethylene or propylene through established oxidative hydrogenation chemistry. The technology is scalable and adaptable for laboratory, pilot, and commercial-scale applications using multiple reactor tubes with the same dimensions. 

Initial life cycle analysis (LCA) indicates that when renewable power is used, this method can utilize 0.92 tons of CO2 per ton of olefin product. By adopting this technology to produce 50% of the projected 2030 olefin capacity, at least 500 million tons of CO2 emissions could be avoided. 

3. UOP Oleflex  

The UOP Oleflex technology is developed by Honeywell, a multinational conglomerate corporation headquartered in Charlotte, North Carolina, providing sustainability solutions and high productivity and performance technologies. 

The UOP Oleflex technology is a catalytic dehydrogenation process that converts propane to propylene with high efficiency and flexibility. The technology uses a fully recyclable, platinum-alumina-based catalyst system, which reduces emissions and energy consumption, and a separate reactor and regeneration design for optimal operation and reliability. 

The Oleflex unit is composed of two main sections, namely, a fractionation section and a reaction section. The fractionation section includes a depropanizer, a deethanizer, a propane-propylene splitter, and a selective hydrogenation reactor. 

The reaction section consists of four vertical reactors with independent heater cells, which convert propane to propylene and hydrogen. The process design enables steady-state operation with high yields, and the catalyst is regenerated continuously using UOP's continuous catalyst regeneration (CCR) technology. 

Moreover, advanced PDH technologies such as Oleflex are driving sustainability in the petrochemical industry and also filling the demand-supply gap. This is leading to significant growth in the market. 

According to data insights from BIS Research, the global propane dehydrogenation to propylene market is projected to reach $22.72 billion by 2031 from $10.31 billion in 2022, growing at a CAGR of 9.2% during the forecast period 2022-2031. 

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4. Fluidized Catalytic Dehydrogenation (FCDh)

Fluidized catalytic dehydrogenation (FCDh) technology is a process used to convert propane to propylene using a circulating fluidized bed system. It was invented and piloted by Matt Pretz, a research and development fellow from Dow Chemical Company, based in Midland, Michigan. 

The FCDh system is comprised of an alumina-supported catalyst, which is introduced into a fast-fluidized reactor. Propane is then fed into the reactor and transported to a plug-flow riser reactor. The plug flow reactor transports the catalyst to close-coupled cyclones for rapid propylene production and catalyst separation. The separated catalyst is then recovered with the help of a stripping agent. 

FCDh technology is a low-risk, low-cost, and high-return process that reduces the energy intensity and carbon footprint associated with traditional technologies. It is one of the most economical commercial propane dehydrogenation (PDH) technologies and can be used to construct a stand-alone PDH unit or integrated existing crackers to provide ‘plug and play’ capabilities for a variety of plant configurations. For instance, in July 2019, PetroLogistics, a subsidiary of Koch Industries, licensed FCDh technology for its new stand-alone PDH unit in the U.S. 

5. STAR Process (Steam Active Reforming) Technology

The STAR process (Steam Active Reforming) technology is reliable and inexpensive for creating propylene and butylene from lower paraffins, such as propane and butane. It involves low capital expenditure and a streamlined process flow. It is the propriety technology of Thyssenkrupp Uhde, a company based in Germany providing industrial electrolysis and polymer technologies. 

To initiate the process, propane is first purified in the feed preparation unit, where any possible impurities are eliminated, and the pure propane is then introduced into the reaction section. At this stage, it is mixed with process steam, heated, and finally, transferred to externally heated reformer tubes filled with catalysts. 

The process feed is then cooled in multiple steps, with energy recovery taking place for steam generation and preheating. The cooled process gas is subsequently condensed, and its heat is recovered by heating distillation columns in fractionation units. 

The fractionation unit includes a stripper that eliminates the chemicals, which cannot be condensed, a gas separation unit, and a splitter column. The unconverted propane is returned to the feed preparation unit for further processing. Furthermore, the STAR process is energy-efficient and can be easily integrated into current facilities. 

For instance, in 2022, BASF and Thyssenkrupp Uhde collaborated to optimize the STAR process for sustainability benefits. Through these joint efforts, the companies aim to reduce CO2 emissions and operation costs by decreasing energy consumption by up to 30%. 

The Future of Petrochemical Industry with Sustainable Propylene Production Technologies

The global demand for propylene has been on the rise in recent years due to its extensive use in a wide range of industries, such as packaging, automotive, and construction. However, the supply of propylene has struggled to keep up with this growing demand, resulting in a significant demand-supply gap. 

To address this demand-supply gap, the petrochemical industry has been exploring alternative methods, such as advanced PDH technologies, that offer a more sustainable and cost-effective approach to propylene production. The adoption of these technologies could help bridge the demand-supply gap by enabling more efficient and environmentally responsible production of propylene. 

As we continue to witness the consequences of climate change and environmental degradation, it is more important than ever to prioritize sustainable practices and invest in research and development. 

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