Catalytic Co-Processing of delayed coker light naphtha with other refinery gasoline streams

Attila Lengyel,Szabolcs Magyar,Jenő Hancsók

doi:10.3311/pp.ch.2009-1.01

Attila Lengyel, Szabolcs Magyar + Show 1 more

Open Access

https://doi.org/10.3311/pp.ch.2009-1.01

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Abstract

Upgrading of delayed coker light naphtha is very difficult due to its high diolefin and silicon content. Mixtures of light straight run naphtha and delayed coker light naphtha fractions were hydrotreated in two stages over NiMo/Al 2 O and CoMo/Al 2 O catalysts (diolefin saturation followed by hydrodesulphurization ). The results showed that naphtha fractions free of diolefins, olefins, sulphur and silicon can be produced with the two stage hydrogenation. These are excellent feeds for naphtha isomerization. One-stage selective hydrodesulphurization tests were also conducted with blends of coker naphtha (up to 5 vol%) and fluid catalytic crackers gasoline over CoMo/Al 2 O . Diolefin-free products of < 10 mg/kg sulphur could be produced with a research octane number loss of max. 3.

Highlights

Higher fraction of the heavy and residual oil needs to be converted into valuable hydrocarbon stocks
Rate of HDS was minor at the mild conditions of the first step. (Deep HDS is not required at this stage) Silicon content was completely adsorbed on the NiMo/Al2O3 catalyst at 180 ̊C-190 ̊C. 180 ̊C-190 ̊ was the optimal for diolefin saturation, since both diolefin conversion and silicon uptake took place efficiently
After finding the proper temperature of diolefin saturation, sample collection was performed with the blend containing 10 wt% DCLN (+90 wt% LSRN) at 190 ̊C reaction temperature to produce feed for the HDS step

Summary

Introduction

Higher fraction of the heavy and residual oil needs to be converted into valuable hydrocarbon stocks (gasoline, Jet fuel, gas oils, lube oils, etc.). Integration of delayed coker light naphtha (DCLN) into the processing structure of a petroleum refinery is very difficult due to its composition (0.4-2% sulphur; 40-400 ppmw nitrogen; 1-2% diolefins; 35-45% olefins). There are basically three options: A) injection of DCLN into the riser of fluid catalytic cracking unit (FCC) unit [1]-[2], B) selective diolefin saturation/Si adsorption prior to hydrodesulphurization (HDS), C) co-processing of the DCLN with FCC gasoline. DCLN may be upgraded together with FCC gasoline in HDS unit. Most of the refineries have already started up their units of selective FCC gasoline HDS (minimized olefin saturation, moderate research octane number loss). In this work mixtures of DCLN and light straight run naphtha (LSRN) (up to 20% DCLN) were hydrotreated in two steps to saturate diolefins (first step; NiMo/Al2O3) and to convert heteroatoms containing compounds (CoMo/Al2O3), respectively. Experiments were carried out with mixtures of DCLN (up to 5 vol%) and FCC gasoline

Methods

Results

Conclusion