Catalysis 2024 Issue

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Figure 2 Valid ISCC certifications for co-processing of renewable and circular feedstocks (ISCC)

Plastic contaminants The source of plastic is particularly important, determining the aromaticity, contaminant metals levels, and oxygen con- tent (if present). The most common plastics (polypropylene [PP], and polyethylene [PE], polystyrene [PS]) are low in met- als and oxygen. Waste electrical and electronic equipment (WEEE) along with tyres is the most difficult to co-process and can contain elevated metals and other contaminants. Finally, bio-oil (cellulosic or bio-waste applications) repre- sents the third group and exhibits elevated metals, contami- nants, aromatic content, oxygen, and water content. Many refiners have either conducted or are considering trials for processing plant, animal-based oils, or recycled oils in their units, and some of these have chosen to declare their use through the ISCC. The focus of this review is specifically on the ISCC certification as an indicator of industry trends. ISCC certification is a voluntary programme applicable to the bio-economy and circular economy, including food, feed, chemicals, plastics, packaging, textiles, and renewable feedstock derived from a process using renewable energy sources. A wide variety of biomass, waste and residues, non-biological renewables, and recycled carbon materials can be certified under ISCC. Certification and co-processing Co-processing can cover anything from converting the source material to oils, fuels or chemicals, polymers, or final products. A survey of these certifications can provide a good indication of the industry trends in making R&R products. Since 2010, there have been more than 52,000 certificate requests. Of these requests, more than 26,000 (roughly half) specify FOG as the feed. In 2023 alone, there were more than 3300 requests for processing FOGs (see Figure 2 ), with only 255 for processing waste plas- tic (WP). This number is far lower than for the FOGs, but the increase on a year-by-year basis has been significant since the first WP applications appeared in 2018. There are far fewer bio-oil certificates. Certificates are generally valid for one year, and the numbers include recertification cases. Co-processing trends are clear (Figure 2, line). The first co-processing certificate was in 2018, and the num - ber of certificates has increased significantly since 2020.

Co-processing applications are for a variety of process units, including hydrotreating, steam cracking, FCC, dis- tillation, coker, and many other routes. The number of co- processing certificates has increased from four in 2019 to 118 in 2023. Approximately 40 of the applications were to process FOG, with 11 for WP and eight for bio-oils. While the number of plans to co-process WPO and bio-oils has been considerably lower than that of FOG, there has been an increase over the last couple of years. WP is reaching our waterways and landfills. Globally, there is a need to establish more thorough, efficient ways to recover and recycle the 250+ MM tons/year of highly cost-effective product. Various companies are pursuing more sustainable, systematic approaches to gathering, col- lecting, cleaning, and sorting plastics, establishing them as the recyclable resource they were designed to be. Eleven companies received WP co-processing ISCC status, and many others recycled WP in 2023. Plastics recycling codes Plastics have several classifications of recycling codes, facilitating the collection and disposal of products. The most popular classification, plastic recycling code 1, or pol - yethylene terephthalate (PET), is mechanically recycled or co-processed to provide containers for drinkable products (water, sodas). PET contains elevated oxygen and is hydro- gen deficient. Some mixed plastic waste (MPW) streams contain levels of PET. The oxygen and low hydrogen repre- sent an added concern for PET and MPW. A hydrotreating guard bed or thermochemical conversion technology to remove the elevated contaminants is desired before send- ing it to the FCC unit. For chemical recyclers, high-density polyethylene (recycling code 2), low-density PE (code 4), PP (code 5), and PS (code 6) have desirable properties for units like the FCC. These plastics are high in iso-paraffinic and iso-olefinic (codes 2, 4, and 5) or mono-aromatic (code 6) hydrocarbons and can be cracked to transportation fuels or processed back as plastic monomers. For the FCC, PVC (code 3) will require additional processing due to the high chloride content and hydrogen deficiency. The most difficult WPOs to co-process are WEEE and end-of-use tyres. Computers and other electronics may

Catalysis 2024