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Aug-2018

Low cost gasoline from low octane feed

Naphtha and methanol are the feedstocks for production of high octane, 
low cost gasoline.

STEPHEN SIMS, Elena Lobichenko, IOSIF LISHCHINER and OLGA MALOVA
New Gas Technologies – Synthesis
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Article Summary
Methaforming removes sulphur and converts naphtha and methanol into a high octane, low benzene gasoline blendstock with yields and octane comparable to isomerisation + CCR reforming. Methaforming uses a proprietary zeolite catalyst in a process flow similar to hydrotreating.

This one-step process replaces naphtha desulphurisation, reforming, isomerisation and benzene removal, thereby reducing capital and operating costs to a third of the current best alternative.

The first commercial Methaformer will start up in the summer of 2018. The 150 b/d (6000 t/y) unit will process a variety of naphtha feedstocks. With a projected uplift of >$23/bbl ($200/ton), it will validate the predicted yields and scale-up factors.

An existing idle hydrotreater or reformer can be converted into a commercial Methaformer at low cost. The main applications of Methaforming are:
1. Building a Methaformer instead of a CCR reformer: worth $220 million net present value (NPV) for a 20 000 b/d (860 000 t/y) unit.
2. Converting a semi-regenerative reformer: worth $50 million/year at a retrofit cost of $20 million for a 20000 b/d (860 000 t/y) unit.
3. Instead of isomerisation: worth $10 million/year with $20 million lower capex for a 10 000 b/d (380000 t/y) unit.
4. Upgrade raffinate from aromatics extraction: upgrade 2000 b/d (88000 t/y) worth $18 million/y at a capex of $30 million.

Methaforming process and economics
A third of current cost can be accomplished because Methaforming is a one-step process. Naphtha and methanol go through a unit similar to a hydrotreater at modest pressure and temperature. The products are like reformate: a high octane gasoline blendstock with relatively low sulphur and, importantly, less than 1.3% benzene. Just like a reformer it produces some light end and releases hydrogen. And by desulphurising, there is H2S in the overhead. The inexpensive proprietary zeolite catalyst does not contain precious metals.

The capital and operating costs of Methaforming are comparable to those of a hydrotreater. The process flow in which methanol is used instead of hydrogen looks like that of a hydrotreater without a recycle compressor. The yields are comparable to a CCR reformer except that most of the benzene is converted to toluene and half the methanol becomes water.

Methaforming costs are so much lower because the process replaces four units. The Methaformer charges naphtha, typically full range naphtha, and reduces sulphur by 90%. It replaces the reformer and, because of low benzene production, avoids the need for any benzene reduction steps. Methaforming also effectively processes light naphtha, thereby eliminating the isomerisation unit. In this way, capital and operating costs are reduced to about a third.

The economics for a grassroots 20 000 b/d Methaformer are shown in the first column of Table 1. The first row is for the yields including fuel gas. The next rows are for other operating expense and finally the estimated capex for inside battery limits (ISBL) only. The last row of the Methaforming column shows that the total 20-year NPV for a Methaformer is $1.3 billion. The next column shows the same values for the alternative of HDS + CCR + isomerisation. The last column shows the difference between Methaforming and the alternative process.

The Methaformer is slightly better in yields at $4 million/y. Opex is $14 million/y lower because less equipment is needed. The capex is $106 million less for ISBL. This gives a difference in NPV of $220 million.

Table 1 shows that by using Methaforming, yields are comparable to the CCR reformer while the operating costs and capex are much lower.

Since few grassroots reformers are being built, the largest market for Methaformers is in replacing existing semi-regenerative reformers.

Table 2 uses the same format as Table 1 to show the economics. Focusing on the delta column, Methaformer yields generate over $50 million/y more than semi-
regenerative reforming. It costs $20 million to convert to a Methaformer. As a result, the Methaformer shows over $400 million NPV. Since a Methaformer is similar to a hydrotreater, the unit that is converted is the naphtha hydrotreater in front of the reformer.

Flexible
The process’s flexibility means that it generates several additional economic opportunities. FCC olefins may be used to replace the methanol in a Methaformer. While refinery propylene is usually recovered and upgraded, many refineries leave the ethylene in the fuel gas stream. There is a $500/t uplift for ethylene in a Methaformer, thereby increasing uplift on naphtha by over $11/bbl ($100/t).

Methaforming provides the opportunity to reduce sulphur while increasing octane for the natural gasoline from a natural gas liquids (NGL) plant and for cracked naphthas.

There is keen interest in the US and Western Europe for processing light virgin naphtha (LVN) because the higher anticipated octane requirements drive consideration of isomerisation with expensive recycle. Processing LVN with ethylene shows over $35/bbl uplift ($330/t). In a side-by-side comparison, Methaforming with ethylene shows $10 million/y better yields giving a $110 million better NPV (see Table 3).

Refiners with low octane streams blended to gasoline (for instance raffinate from aromatics extraction) are interested in Methaforming. For a 2000 b/d (88 000 t/y) stream of raffinate, the process, with the added benefit of ethylene, gives a six-month payback and $160 million NPV for this small unit from an uplift of $42/bbl ($350/t, see Table 4).

Process development and testing
The Methaforming catalyst and process were developed, and the operating parameters optimised, in three pilot plants with over 7000 hours of processing. The latest and largest pilot plant started up in 2015 and has a 2 litre reactor and capacity of 38 l/d (0.23 b/d). Based on extensive pilot plant testing, we can reliably predict the results for any naphtha.

A major Russian refiner plans to build an 11 000 b/d (470 000 t/y) Methaformer for start-up in 2020 and has funded a new, larger and more sophisticated pilot plant to confirm the design. This pilot plant, to be located in Moscow at the High Temperature Research Institute, will start up in October 2018.

 Its configuration will be a three-stage 9 litre reactor with a capacity of up to 2 b/d (90 t/y) designed for continuous operation and testing of the products. It will include enhanced features to enable co-feeds of methanol and/or other alcohols of varying concentrations, and olefin gases such as in FCC dry gas. Two additional features will address stricter gasoline specifications: on-purpose hydrotreating capability to increase desulphurisation from 90% to 99% and benzene recycle for less than 1% in the product Methaformate.
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