โ† HEFA Yield Analysis ยท ๐Ÿงฎ Isomerization Calculator โ†’

HEFA Yield Slider โ€” RD โ†” SAF โ†” Naphtha Trade-offs

Supporting analysis for "The Specification Barrier" โ€” How product mix shifts affect refiner economics

Figure A. HEFA Product Slate vs. SAF Yield โ€” Cracking Pathway

Product distribution as a function of SAF yield for C18-dominant feedstocks (soybean, jatropha) via hydrocracking. As SAF yield increases, RD yield decreases disproportionately โ€” the excess is lost to naphtha and gas. Shaded bands show the range between Pearlson (2013, selective cracking) and Zech (2018, 90% cracking rate). Central estimates shown as solid lines.
Product Yield (wt% of feed) SAF Yield (wt% of feed) 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 13% 30% 48% 68% 44% 16% 3% 16% SAF Renewable Diesel Naphtha LPG / Fuel Gas โš  Non-linear zone Naphtha penalty accelerates
Sources: Pearlson et al., Biofuels Bioprod. Bioref. 7:89โ€“96 (2013); Zech et al., Applied Energy 231:997โ€“1006 (2018); Robota et al., Energy Fuels 27:985โ€“996 (2013). Central estimates weighted 60/40 toward Pearlson for modern catalyst relevance.

Figure B. Naphtha Yield Loss vs. Cracking Conversion โ€” Robota et al. (2013)

Normalized naphtha loss (C8โป fraction as % of C9โ€“C15 jet-range product) at three single-pass cracking conversions over Pt/US-Y zeolite. Below ~60% conversion, naphtha losses are roughly constant (~41โ€“44%). Above 60%, secondary cracking of already-cracked products causes a catastrophic increase to 75%.
Naphtha Loss (% of jet fraction) Single-Pass Cracking Conversion (%) 0 20 40 60 80 0 25 50 75 100 Linear regime Non-linear regime 41% 43% conv. 44% 59% conv. 75% 93% conv. Secondary cracking of products kicks in
Source: Robota et al., "Converting Algal Triglycerides to Diesel and HEFA Jet Fuel Fractions," Energy & Fuels 27:985โ€“996 (2013). Catalyst: 0.5% Pt/US-Y zeolite, 800 psig. Feedstock: algal triglycerides (85% C18, 10.5% C16).

Figure C. Two Pathways to SAF โ€” Cracking vs. Isomerization

Comparison of hydrocracking (legacy) and hydroisomerization (modern) approaches to SAF production from C18-dominant HEFA feedstocks. Isomerization preserves the carbon backbone, shifting boiling points into the jet range by branching without C-C bond cleavage. This eliminates most naphtha/gas losses.
SAF Yield at ~50% Target: Cracking vs. Isomerization Hydrocracking Pathway (Pearlson 2013 / Zech 2018) Losses 12% Gas 8% Naphtha 16% RD 16% SAF 48% Jet + Diesel 64% Hydroisomerization Pathway (Neste 2024 / UOP Patent 2025) Losses 13% Naph ~4% RD 26% SAF 55% Jet + Diesel 81% +17 pp jet+diesel selectivity
Left bar: central estimate from Pearlson (2013) and Zech (2018) at maximum SAF mode. Right bar: estimated from Neste NEXBTL campaign data (Ketjen/ERTC 2024, 74 wt% SAF of liquid product) and UOP Patent US 2025/0026990 (SAPO-11 catalyst, >80% jet yield claimed). Isomerization values are approximate โ€” detailed product slates not publicly available.
โš  Important distinction: Most published HEFA yield models (Pearlson, Zech, Robota) assume hydrocracking โ€” breaking C18 chains into C9+C9 with inevitable naphtha losses. Modern producers (Neste, likely others) are increasingly using hydroisomerization over SAPO-11 catalysts, which shifts boiling points into jet range by branching C17/C18 chains without breaking them. This preserves carbon, eliminates most naphtha losses, and produces higher energy-density SAF. The two pathways have fundamentally different yield economics.
Cracking rule of thumb (per +10% SAF): โˆ’14% RD, +3.6% naphtha, +1.0% gas. Non-linear above 40% SAF โ€” naphtha penalty accelerates catastrophically (Robota: 41% โ†’ 75% normalized naphtha loss between 59% and 93% cracking conversion).
Isomerization rule of thumb (per +10% SAF): ~โˆ’10% RD, <1% naphtha. Near 1:1 RDโ†’SAF conversion. Linear through at least 70% SAF (Neste demonstrated 74%). Higher Hโ‚‚ consumption but no carbon loss to light ends.

Pearlson (2013) โ€” Soybean Oil

ProductMax DistillateMax Jetฮ”
SAF12.8%49.4%+36.6
RD68.1%23.3%โˆ’44.8
Naphtha1.8%7.0%+5.2
LPG1.6%6.0%+4.4
Hโ‚‚ in2.7%4.0%+1.3
Biofuels Bioprod. Bioref. 7:89โ€“96. MIT/Aspen Plus model.

Zech (2018) โ€” Jatropha Oil

ProductDiesel ModeJet Modeฮ”
SAF12.3%46.2%+33.9
RD66.9%8.2%โˆ’58.7
Naphtha4.5%27.5%+23.0
Fuel gas3.0%5.4%+2.4
Hโ‚‚ in29.8 kg/t35.7 kg/t+5.9
Applied Energy 231:997โ€“1006. DBFZ/ASPEN model, 500 kt/yr, 90% cracking rate.

Robota (2013) โ€” Cracking Severity vs. Naphtha Loss

Cracking ConversionTemp (ยฐC)C8โป NaphthaNaphtha/Jet RatioMeets โˆ’47ยฐC FP?
43%26815%41%Doubtful
59%27221%44%Likely
93%27843%75%Certainly
Energy & Fuels 27:985โ€“996. Algal triglycerides, 0.5% Pt/US-Y zeolite, 800 psig.
Research gap: No published paper directly compares isomerization vs. cracking yield curves at matched SAF fractions with the same feedstock. The ลukasiewicz-ICSO group (Renewable Energy, 2024) studied Pt/SAPO-11+Alโ‚‚Oโ‚ƒ for rapeseed hydroisomerization, and UOP Patent US 2025/0026990 describes the approach in detail, but peer-reviewed comparative data is scarce. This is a publishable gap.