EHDS Technology - A White Paper final version

Technical White Paper: Extraction & Hydrodesulfurization (EHDS) Technology for FCC Gasoline

A Revolutionary Approach to Ultra-Low Sulfur and Octane Preservation

By Hebei Refining Technologies Co., Ltd.
Authors: Tianzhen Hao, Jinsen Gao, Dezhong Li, Liang Zhao, Zhiyuan Lu, Xingying Lan
Patent Number: US 9,856,423 B2
Date of Issue: January 2, 2018
Assignees: Tianzhen Hao (Hebei, CN), China University of Petroleum-Beijing (Beijing, CN)

Executive Summary

Hebei Refining Technologies Co., Ltd. (HRT) presents the Extraction & Hydrodesulfurization (EHDS) technology, a patented process (US 9,856,423 B2) developed over two decades to address the refining industry’s challenge of deeply desulfurizing Fluid Catalytic Cracking (FCC) gasoline while preserving octane ratings. EHDS integrates solvent extraction with selective hydrodesulfurization, achieving:

• Sulfur content: Reduced to <10 ppm, often <5 ppm, surpassing China VI and Euro VI standards.
• Octane loss: Limited to <0.2–1.0 units, compared to 2.0–4.0 units in conventional methods.
• Hydrogen efficiency: Consumption decreased by 50–67%.
• Olefin management: Preserves high-octane linear olefins while targeting less valuable cyclic and branched olefins.

This white paper outlines the technical foundation, process mechanics, industrial validation, and economic and environmental benefits of EHDS, positioning it as a transformative solution for sustainable refining.

1. Introduction

1.1 Background

FCC gasoline, accounting for 70–80% of gasoline products globally, is a cornerstone of fuel production but presents significant environmental challenges due to its high sulfur content (150–1,200 ppm). Stringent regulations, such as China’s State V (<10 ppm sulfur) and Euro VI standards, demand advanced desulfurization technologies. Traditional methods like S-zorb, RSDS, and Prime-G+ achieve low sulfur levels but compromise octane value and require substantial hydrogen, increasing costs and complexity.

1.2 The Challenge

The refining industry faces a dual imperative: reducing sulfur to meet environmental standards while retaining octane-critical olefins (40 vol% in FCC gasoline). Conventional hydrodesulfurization (HDS) methods often:

• Saturate olefins, causing octane losses of 2.0–4.0 units.
• Demand high hydrogen use (e.g., H₂/Oil ≥80%).
• Generate significant tail gas emissions.

EHDS offers a novel solution by combining solvent extraction with a C5 reflux mechanism and selective HDS, minimizing these drawbacks.

1.3 Objective and Significance

EHDS aims to:

• Achieve sulfur levels <10 ppm with yields >95%.
• Limit octane loss to <0.2–1.0 units.
• Reduce hydrogen reliance and enhance refinery adaptability.

Its significance lies in delivering environmental compliance, economic efficiency, and compatibility with existing systems, making it a game-changer for global gasoline production.

2. Technical Foundation and Innovation

2.1 Sulfur Distribution in FCC Gasoline

EHDS leverages the distinct sulfur profiles across gasoline fractions:

• C5 Fraction (<40°C): Mercaptan sulfur, removable via extraction.
• C6 Fraction (40–80°C): Thiophene sulfur, extractable like benzene.
• C7 Fraction (70–110°C): Methylthiophene sulfur, extractable like toluene.
• C8+ Fraction (>110°C): Alkylthiophenes and thioethers, suited for selective HDS due to lower olefin content (16 wt%).

This distribution enables a hybrid approach: extraction for lighter fractions (C5–C7) and HDS for heavier fractions (C8+).

2.2 Core Innovation: Solvent Extraction with C5 Reflux

The process employs a proprietary weakly alkaline GL solvent, enhanced by a saturated C5 hydrocarbon reflux:

• Mechanism: C5 reflux displaces olefins from the solvent, preserving octane-critical components while extracting sulfur compounds.
• Efficiency: Sulfur removal ≥99.5%, olefin loss ≤5% (vs. 15–25% in traditional solvents).

2.3 Process Overview

EHDS operates in three integrated stages:

1. Three-Cut Distillation:
   • Light Cut (LCN): C5–C7, <50 ppm sulfur.
   • Middle Cut (MCN): C6–C8, 150–1,200 ppm sulfur.
   • Heavy Cut (HCN): C8+, 20–100 ppm sulfur.
2. Solvent Extraction Desulfurization: Targets LCN and MCN, using the GL solvent.
3. Selective Hydrodesulfurization: Processes HCN with proprietary catalysts, optimizing olefin retention.

3. Process Description

3.1 Solvent Extraction Process

• Feed Introduction: Gasoline enters the extraction tower at the lower-middle section; solvent enters from the top.
• C5 Reflux: Saturated C5 hydrocarbon is injected at the tower bottom.
• Operating Conditions:
  • Top temperature: 55–100°C (preferred 65–80°C).
  • Bottom temperature: 40–80°C (preferred 50–60°C).
  • Top pressure: 0.2–0.7 MPa (preferred 0.5–0.6 MPa).
  • Solvent-to-feed ratio: 1.0–5.0 (preferred 2.0–3.0).
  • C5-to-feed ratio: 0.1–0.5 (preferred 0.2–0.3).
• Outputs:
  • Desulfurized gasoline (top).
  • Sulfur-rich solvent with C5 hydrocarbons (bottom).

3.2 Solvent Selection and Post-Processing

• Solvents: Tetraethylene glycol, sulfolane, or dimethyl sulfoxide, with 0.6–0.8% water content.
• Post-Extraction:
  • Desulfurized gasoline washed with 2–4% water.
  • Sulfur-rich solvent processed via distillation (150–180°C, 0.15–0.3 MPa) and recycling towers (130–180°C, 0.015–0.05 MPa) to recover C5 hydrocarbons and solvent.

3.3 Flexible Embodiments

EHDS adapts to various refinery needs:

• Embodiment 1: Light fraction alkali extraction, medium fraction solvent extraction, heavy fraction HDS.
• Embodiment 2: Full-range extraction with selective HDS, compatible with S-zorb or RSDS.

4. Industrial Validation and Applications

4.1 Experimental Validation

• Case 1: Feed (200–400 ppm sulfur), sulfur <5 ppm, yield >95%.
• Case 2: Feed (600–800 ppm sulfur), sulfur <10 ppm, yield >95%.

4.2 Real-World Success

• Shandong Yatong Petrochemical (2015): 400,000 tpy, sulfur <10 ppm, octane loss 1.0 unit, hydrogen savings 42%.
• Hengyuan Refining Malaysia (Formally Shell Malaysia) (2022): 1.1 million tpy, sulfur <70 ppm, export-grade gasoline.
• Hebei Xinhai Petrochemical (2023): Full-distillate processing, flexible sulfur targets (20–100 ppm).

4.3 Refinery Integration

EHDS leverages existing equipment (e.g., aromatics extraction towers), reducing capital costs and enhancing compatibility with S-zorb, RSDS, and Prime-G+ systems.

5. Comparative Analysis and Benefits

5.1 Technological Comparison

Technology	Sulfur (ppm)	Octane Loss	Hydrogen Use
S-zorb	<10	1.0–2.0	High
RSDS	<10	3.0–4.0	High
Prime-G+	<10	3.0–4.0	Moderate
EHDS	<5–10	<0.2–1.0	Low

5.2 Economic and Environmental Excellence

• CAPEX: $2.6–2.9M USD/1M tpy (vs. $3.6–4.3M for traditional HDS).
• OPEX: $500–570 USD/ton (vs. $715–860).
• Environmental: Zero tail gas emissions, minimal waste (<500 kg/year vs. 2 tons/day).

6. Conclusion

EHDS technology resolves the refining industry’s sulfur-octane dilemma with unparalleled efficiency and adaptability. Proven across 7.2 million tpy of global installations, it delivers ultra-low sulfur levels, minimal octane loss, and significant cost savings while advancing environmental stewardship. Hebei Refining Technologies Co., Ltd. invites partnership to drive the future of clean energy refining.

Contact Us

• Wang Jingfeng, Director of International Business
  Email: wangjingfeng@hbreftech.com (mailto:wangjingfeng@hbreftech.com) | Phone: +86 139 3079 3295
• Anthony Wang, Deputy Director of International Business
  Email: wangyan@hbreftech.com (mailto:wangyan@hbreftech.com) | Phone: +86 138 1125 4964

Appendices: Flow diagrams, patent details, and performance data available upon request.

References

• U.S. Patent No. 9,856,423 B2, "Process for Deeply Desulfurizing Catalytic Cracking Gasoline," issued January 2, 2018.
• Chinese Patent Application No. 201310581366.8, filed November 18, 2013.
• International Application No. PCT/CN2014/070817, filed January 17, 2014.