Refining India 2023 Conference Newspaper

ERTC 2023

refining india 2023

CO 2 -derived bio-based polycarbonate: A route towards sustainability ANdrew hubbell citgo, brandon burns shell energy and chemicals, and victor batarseh w.r. grace & c0 Reducing environmental impact of FCCs with wet gas scrubbers by using SOx additives

Monikangkana Talukdar, Ujjal Haldar, Yogesh P Patil AND Bennet C HP Green R&D Centre, Hindustan Petroleum Corporation Limited

The continuous depletion of fossil-based feedstock and excessive emission of car- bon dioxide (CO₂) has affected the ecologi- cal environment and become a significant concern. One way to overcome these prob- lems is to adopt and develop novel green chemical processes based on renewable resources (biomass, CO₂), replace the con- ventional chemical processes with high energy consumption and pollution, and realise the transformation and upgrada- tion of the chemical industry. Polycarbonates (PCs) are high-perfor- mance tough, amorphous, and transparent engineering plastics that have combined benefits of transparency and optical clar- ity with exceptional impact resistance, tensile strength and dimensional stability. These characteristics widen its applica- tion in the production of protective shields, lenses, food and containers and automo- tive parts. SOx reduction additives have long been used in the FCC to limit SOx emissions to the atmosphere in units without wet gas scrubbers (WGSs). Units with WGSs typi- cally do not require SOx additives to main- tain regulatory compliance. However, they can be implemented to offset caustic usage, reducing operating expenses and limiting the lifecycle CO₂e of operating the FCC while also converting waste streams to usable products. Traditionally, PC is synthesised from phosgene and bisphenol A (BPA), a petro- chemical feedstock that is an endocrine disrupter likely to cause reproductive, developmental, and other health issues. BPA-free PCs are, therefore, highly desira- ble, and the use of BPA has been forbidden in food packaging and medical equipment, especially in children’s milk bottles, owing to its chronic toxicity. The end-use applications such as auto- motive and aircraft components, optics, and medical equipment of bio-based PC make it a suitable drop-in substitute for synthetic PC. Bio-based PC is possibly expected to take over some market share of PMMA and acrylics because of its high impact resistance and high durability in key end-use industries such as medical, building, and construction. Case Studies In both case studies, the first step to imple- menting SOx additives for WGS caustic reduction was to understand the caustic consumption without using additive. To do this, multivariable linear regressions were developed to predict additive-free caus- tic consumption from parameters, includ- ing feed sulphur mass flow rate. For both cases, close alignment between actual and predicted caustic consumption confirms a good fit for the regression model. However, the market growth of bio-based PC is anticipated to be negatively affected due its high manufacturing cost and com- plex synthesis process. Increasing bio- based PC application scope in glass and automotive components owing to protec- tion from UV light is anticipated to bolster market growth in the foreseeable future. Asia Pacific was the largest bio-based Utilising a combination of the baseline data and Grace’s proprietary SOx additive performance model, an evaluation was con- In these case studies, lifecycle CO₂e reduction is achieved by limiting the amount of NaOH being produced, shipped to, and utilised by the FCC WGS. The waste avoidance described here is driven by the additive capturing the sulphur, which would be wastewater-dissolved solids and redirecting it to generate ele- mental sulphur. A full-burn FCC at CITGO Lemont’s refinery and a partial-burn FCC at a Shell refinery on the US Gulf Coast are examined here. Introduction Over the last 80 years, the FCC has played a critical role in the refining industry and continues to adapt to shifting industry conditions. The next opportunity to dem- onstrate the flexibility of the FCC is to re-optimise the unit to reduce its carbon intensity. Grace remains committed to sup- porting the industry with creative solutions to drive the highest profitability operation while minimising the FCC’s environmental footprint. The case studies below examine Grace’s collaboration with refiners to main- tain environmental compliance for SOx emissions in a more cost-effective and sus- tainable manner.

delivery systems. Its biodegradable prop- erties make it an attractive choice for creat- ing implants that can safely degrade within the body over time. Its ability to combine environmental sustainability with versatile performance makes it a key player in the transition towards a more eco-conscious and technologically advanced future. We have developed isosorbide-based PCs using a CO₂-derived carbonate mol- ecule, such as dimethyl carbonate and diphenyl carbonate having high molecu- lar weight. These have been developed via a non-phosgene route using newly found economically viable metal-containing This analysis confirms that implement- ing Grace’s EMISSCIAN TM SOx additive for WGS caustic reduction at both the CITGO Lemont and Shell US Gulf Coast FCCs not only provided significant Opex reduc- tion but also reduced the Scope 3 carbon emissions associated with operating the FCC and diverted sulphur from a waste stream to the sulphur plant, creating a sell- able product. homo- and heterogeneous catalyst sys- tems. Notably, designed catalyst systems showed better performance compared to other well-known metal catalyst, even at mild reaction conditions. In addition, the synthesised PC shows better optical clar- ity reflected by its low haze value. Overall, an effort has been made to develop a bio-renewable PC, with an approximate reduction of 60% of fossil fuel resources compared to conventional PC and a car- bon footprint reduction of approximately 20% based on carbonate source. Thus, the development of CO₂-derived bio- based PC aligns with the growing demand for sustainable materials and the need to reduce the environmental impact of plastic production. As the world seeks innovative solutions to combat climate change and reduce plastic pollution, this technology offers a compelling pathway to greener and more sustainable plastics production. References 1 Yong S E, Rhee H W, Seunghan S, Journal of Industrial and Engineering Chemistry , 2016. 2 Haldar U, Talukdar M, Patil Y P, Chelliahn B, Rao B R, Indian Patent, 202241066356, 2022. Conclusions Evaluation of the activities at CITGO and the Shell refinery show that implementing SOx additive for WGS caustic abatement has the potential to deliver sustainabil- ity benefits in addition to Opex reduction. The sustainability benefits include a reduc- tion in Scope 3 emissions associated with caustic production and transportation as well as converting the sulphur destined for waste into a usable product in both full- and partial-burn FCC units. Implementing Grace’s SOx additive, EMISSCIAN, allows refiners to achieve these benefits while also minimising SOx emissions compli- ance Opex by delivering the highest flue gas sulphur reduction per pound of addi- tive across a variety of applications. Grace remains dedicated to continually investing in the development of novel solutions and manufacturing capabilities to better serve its customers. 3 Seul A P, Jaehoon C, Sungbin J, Jonggeon J, Kang M L, Sung Y H, Dongyeop X O, Jeyoung P, Polymer 116, 2017, 153-159. 4 Wenjuan F, Zhencai Z, Zifeng Yy, Yaqin Z, Fei X, Chenhao L, Hongzhe A, Ting S, Yunjun L, Suojiang Z, G reen Chem ., 2020, 22, 4550. Contact: corphqo@hpcl.in additive in partial burn, significant sustain- ability benefits are still realised through a reduction in lifecycle CO₂e emissions and waste avoidance. Operation without SOx additive requires greater amounts of caustic to be produced, then shipped to the refiner, and treated as total dissolved solids in wastewater plants. Additional details on data and calculations associated with the lifecycle CO₂e changes in the system when considering this switch from caustic to a combination of caustic and SOx additive are shown in Table 1 . Annualised CO₂e reduction totals were substantial at more than 8,100 tons combined between the two FCCs, which equates to saving the emissions from com- busting 135.5 million standard cubic feet (MMSCF) or 140,300 million BTUs of nat- ural gas.

Primary analysis

CITGO Lemont FCC

Shell US Gulf FCC (partial burn)

(full burn)

SOx additive usage (lbs/day)

510

400

Caustic usage and delivery reduction

Usage, 11.8 (dry sT/day) Deliveries, 1.1 per day

21.3% (combined)

H OH

SOx additive deliveries (deliveries/day)

0.01 16.3

0.01

6.1

Lifecycle CO

HO 2e reduction (tons/day)

OH OH

O R1

Annualised lifecycle CO 2e

reduction (tons/year)

5,959

O 2,230

Plant based feedstock Other impacts Waste sulphur converted into sellable product (tons/day) Glucose Waste sulphur converted into sellable product (tons/year)

Sorbitol

Isosorbide

Polycarbonate

9.5

4.2

3,461

1,536

SOx additive to cement kiln (lbs/day)

510

400

Figure 1 Schematic representation of bio-based polycarbonate process

Table 1 Summary of sustainability benefits associated with implementing SOx additive in combination with WGS caustic at CITGO

try, and government agencies will play a crucial role in advancing research, scal- ing up production, and expanding market reach, positioning CO₂-derived bio-based PC as a key player in the sustainable mate- rials market. The application insights of CO₂-derived bio-based PC represent a remarkable advancement in sustainable materials sci- ence. This innovative material, synthesised by incorporating CO₂ as a feedstock into the production process, holds immense potential across various industries. One of its most prominent applications lies in the realm of packaging materials. It offers exceptional durability and barrier proper- ties, making it an ideal choice for creat- ing eco-friendly packaging solutions. It not only reduces reliance on fossil fuels but also minimises the carbon footprint associ- ated with packaging waste. Moreover, this innovative material finds utility in the auto- motive sector, where it can be employed for manufacturing lightweight and robust components. The ability to reduce vehicle weight contributes to improved fuel effi- ciency and reduced greenhouse gas emis- sions, aligning with the global push for greener transportation. In the field of electronics, CO₂-derived bio-based PC serves as an excellent insu- lating material due to its high thermal sta- bility. It can be used in the production of electrical components and circuit boards, enhancing the overall performance and lon- gevity of electronic devices while reducing their environmental impact. Furthermore, this sustainable PC has shown promise in medical applications, such as the develop- ment of bio-compatible implants and drug The deep partial-burn Shell US Gulf Coast FCC examined here is a residual fluid catalytic cracking unit (RFCC) that typically operates at ~100,000 barrels per day with a 22.5 feed API and sulphur content of 0.7-1.1 wt%. This FCC rou- tinely operates with flue gas CO between 5-7 vol%. Grace collaborated with Shell, leveraging unit data and Grace’s proprie- tary model to identify the optimum caustic reduction to minimise SOx emissions com- pliance operating expenses. Due to operation in partial burn and lim- ited oxygen availability for oxidising SO₂ to SO₃, SOx additive is less effective in this unit than the full-burn FCC studied in the previous case study. As a result of partial-burn operation and other unit parameters, the target caus- tic reduction for maximising Opex sav- ings was 20-25% at the Shell refinery. Implementation of 400 lb per day of SOx additive, preblended with fresh catalyst, drove a 21.3% caustic reduction. This resulted in $0.5-1.0 million per year in sav- ings, assuming a $1,000 per dst caus- tic price. Despite the challenges for SOx tic usage without additive was compared to the actual caustic usage with SOx additive, and the gap between actual and predicted caustic consumption signifies the reduction achieved with the additive. The refinery averaged 510 lb per day of SOx additive usage and 11.8 dst per day of caustic reduction, realising net SOx control Opex savings of $2.5-3.5 million per year (annualised after excluding a period of unu- sual operation during turnarounds at other process units). This was calculated assum- ing a $1,000 per dst caustic price.

PC market in 2013 and is expected to wit- ness significant growth in bio-based PC demand owing to increasing bio-based thermoplastics demand in electronics and automotive applications. Another major bio-based PC regional market is Europe, on account of stringent regulations related to the use and disposal of petrochemi- cals. The market growth of bio-based PC in forthcoming years is expected to be driven by the rapid industrialisation and adoption of bio-polymers in emerging economies such as Brazil, China, India, and Malaysia. ducted to determine the optimal balance between additive usage and WGS caustic required to minimise total emissions com- pliance operating expenses. This type of analysis demonstrates that there is a wide range of SOx additive rates over which operating expenses (Opex) can be reduced. The full-burn CITGO Lemont FCC unit typically processes 60,000 barrels per day of feed with an API of 18 and sulphur content of 2.5 wt%. For this operation, the the development of CO₂-derived bio- based PC aligns with the growing demand for sustainable As consumer awareness of environmen- tal issues continues to rise, CO₂-derived bio-based PC is likely to gain traction as a viable solution for reducing plastic pol- lution and mitigating climate change. Collaborations between academia, indus- materials and the need to reduce the environmental impact of plastic production provided significant Opex reduction but also reduced Scope 3 emissions associated with the FCC unit’s WGS consumes ~24.5 dry short tons (dst) of caustic (NaOH) per day. The CITGO Lemont and Grace teams collaborated to develop a comprehensive analysis to help set SOx additive rates throughout the year as caustic pricing, feed quality, and feed rates shifted. The evaluation revealed additive rates ranging from 400 to 700 lb per day max- imised the total SOx compliance Opex savings by appropriately balancing SOx additive and WGS caustic. The same regression model utilised to describe caus- Implementing EMISSCIAN SOx additive not only

Contact: ????????????/

Published by

Managing Director Richard Watts

PTQ is the industry-leading magazine covering developments in the refining, gas and petrochemical processing industries.

Managing Editor Rachel Storry rachel.storry@emap.com

Publisher of PTQ / Digital Refining

Editorial Assistant Lisa Harrison lisa.harrison@emap.com

Business Development Director Paul Mason Tel: +44 (0)844 5888 771 sales@petroleumtechnology.com

Graphics Peter Harper