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June 2024

Special Focus: Process Optimization

Hydrogen-rich content gasoline: A new concept for paraffinic gasoline reformulation

Several refiners are evaluating a new gasoline-formulation technology called hydrogen (H2)-rich-content (HRC) gasoline. This patented technology uses low-sulfur, H2-rich refinery blendstocks like straight-run gasoline, isomerates, alkylate, butanes and renewable naphtha in gasoline blends, and adds aromatic amines (a high-octane gasoline additive) to make a drop-in specification gasoline.

HRC Fuels: Burger, J.  |  Byrne, D.
Hoekstra Trading LLC: Hoekstra, G.

Several refiners are evaluating a new gasoline-formulation technology called hydrogen (H2)-rich-content (HRC) gasoline. This patented technology uses low-sulfur, H2-rich refinery blendstocks like straight-run gasoline, isomerates, alkylate, butanes and renewable naphtha in gasoline blends, and adds aromatic amines (a high-octane gasoline additive) to make a drop-in specification gasoline. The authors’ company has developed ways that require little to no capital to apply this technology for refineries within months, not years.

While it may seem counter-intuitive to favor the use of some low-octane blendstocks like straight-run gasoline and renewable naphtha in gasoline, this concept works because ethanol has a very high octane blending value with paraffinic naphthas. The addition of aromatic amines makes up the balance of the required octane.

Interest in this technology has increased because HRC gasoline technology effectively addresses many of the issues caused by evolving gasoline regulations:

  1. The octane-sulfur bottleneck is caused by the implementation of the Tier 3 gasoline sulfur standard in the U.S., which requires an annual average maximum of 10 parts per million (ppm) sulfur in gasoline sold in the U.S. Many U.S. refineries are unable to desulfurize gasoline down to 10 ppm without also downgrading the octane of their gasoline pool. Since 2021, this new bottleneck in gasoline production has been reducing gasoline supply, increasing gasoline prices and decreasing the profitability of North American refineries. Refiners suffering from this bottleneck have the option to purchase gasoline sulfur credits; however, the price of these sulfur credits increased ten-fold in 2023 to $0.07/gal of gasoline and remains at that high level. HRC gasoline technology provides additional octane to allow refiners to desulfurize fluid catalytic cracking (FCC) naphtha more deeply, which saturates olefins. Desulfurized FCC naphtha can be blended into HRC gasoline, which uses ethanol octane synergy to compensate for the olefin octane.
  2. The skyrocketing price of incremental aromatic octane blendstocks is a byproduct of the octane-sulfur bottleneck exacerbated by the increasing demand for benzene, toluene and xylenes (BTX) feed. Prices for these stocks have soared, as indicated by the five-fold increase in the retail pump price differential between premium and regular gasoline. HRC gasoline technology solves the octane problem by providing less-expensive octane to replace aromatic octane.
  3. Benzene credits in gasoline are very similar to sulfur in gasoline credits. If refiners struggle to meet the lower standard for benzene in gasoline, they have the option to purchase benzene credits. This market has not blown out or witnessed significant growth the way sulfur credits have, but having to purchase benzene credits reduces the profitability of making gasoline. Because HRC gasoline is predominantly paraffinic, it contains low to no benzene. This can quickly transform a benzene credit buyer to a benzene credit seller.
  4. Meeting gradually increasing renewable volume obligation (RVO) requirements is another increasing cost for refiners. While refiners receive renewable identification number (RIN) credits for the ethanol required in gasoline, the ethanol credits are only adequate to cover ethanol RVOs. Refiners still must purchase credits for the hydrocarbon portion of their fuel production. HRC gasoline technology facilitates blending significant volumes of renewable naphtha into gasoline. This allows refiners to capture RIN credits and Low Carbon Fuel Standard (LCFS) credits from qualifying renewable blendstocks. The added profit can be substantial.

These added costs have been offset by very high refining margins in recent years, helping to ease the strain on refiners in the short term. However, experienced industry professionals know that periods of low margins will come eventually—when they do, those who have prepared will survive. The authors’ company has consistently shown that the production cost of HRC gasoline can be $6/bbl lower than conventional aromatic-based gasoline, not counting RINs or LCFS credits.

Some of these savings can be passed on to consumers. In response, politicians will be looking for ways to promote these savings for their constituents.

How does HRC technology work? Part 1: Ethanol octane synergy

H2-rich streams like straight-run gasoline and renewable naphtha are normally considered too low in octane for use in gasoline blending. However, the HRC concept works by exploiting the fact that, when ethanol is added to H2-rich paraffinic gasoline blendstocks, a larger octane boost is achieved, helping finished blends meet octane requirements. This is illustrated in FIG. 1.

FIG. 1. HRC fuel technology exploits ethanol octane synergy with H<sub>2</sub>-rich hydrocarbons.
FIG. 1. HRC fuel technology exploits ethanol octane synergy with H<sub>2</sub>-rich hydrocarbons.

 

The octane blending value of ethanol is 170 when blended with renewable naphtha, but only 98 when blended with gasoline-range aromatics. The octane boosting synergy with H2-rich blendstocks is called ethanol octane synergy. Ethanol octane synergy also applies to all paraffinic (H2-rich) blendstocks: alkylate, isomerate, butane, virgin naphthas and renewable naphthas.

Because all U.S. gasoline today contains ethanol, this octane-boosting leverage is available to increase the octane of finished gasoline but is not typically exploited with today’s gasoline blending strategies. Ethanol octane synergy works even better with 15% ethanol (E15) gasoline blends. The octane boost is the same, and with 50% more ethanol, so there is that much more octane available for gasoline blending.

Ethanol octane synergy in practice

As illustrated in FIG. 2, most U.S. refineries make an 84 octane refinery base blend called conventional blendstock for oxygenate blending (BOB) from several streams made in the refinery. When adding 10% ethanol to the 84 octane BOB, 87 octane regular gasoline—known as E10—is produced. In this case, the ethanol blending octane is 115.

FIG. 2. Segregating H&lt;sub&gt;2&lt;/sub&gt;-rich blendstocks enables the capture of a synergistic 150 octane blending value of ethanol.
FIG. 2. Segregating H<sub>2</sub>-rich blendstocks enables the capture of a synergistic 150 octane blending value of ethanol.

 

As an alternative, a refinery could blend a H2-rich content BOB that has an octane of 81 (instead of 84). When adding 10% ethanol, the same 87 octane regular gasoline is produced. The boost from 81 octane to 87 octane is the ethanol octane synergy that comes only when blending ethanol with a H2-rich content BOB. This blending strategy captures the value of the ethanol octane synergy—the ethanol octane blending value is 35 points higher, reaching 150 octane.

Part 2: Aromatic amines

The patented HRC gasoline formulation calls for highly paraffinic gasoline blendstocks and the use of aromatic amines to achieve the desired standard octane specifications for finished gasoline. Aromatic amines (FIG. 3) are gasoline boiling range compounds that have very high octane blending values (about 425 octane). By U.S. Environmental Protection Agency (EPA) regulations, they are substantially similar to gasoline and can be registered as gasoline additives with the EPA. Each individual gasoline additive is limited to 0.25 wt% in finished gasoline, and the total of all gasoline additives must be limited to 1 vol%.

FIG. 3. Aromatic amines capture additional octane value.
FIG. 3. Aromatic amines capture additional octane value.

 

The authors’ company has conducted many evaluations of how to use this patented HRC gasoline technology for prospective users. In every situation, there are strong economic incentives to maximize the use of aromatic amines in HRC gasoline blends. This is because higher volumes of aromatic amines minimize the need to purchase high-priced iso-octane or alkylate (valuable, high-octane paraffinic stocks).

Alternatively, higher volumes of aromatic amines maximize the incentive to blend low-octane paraffinic stocks, such as renewable naphtha or light straight-run naphtha from paraffinic crudes from the Bakken or Eagle Ford shale fields.

Maximizing aromatic amines to the U.S. EPA limit maximizes profitability.

Applying HRC technology in a refinery

A high-level diagram of how to quickly apply the technology in a refinery and obtain the benefits of HRC gasoline is shown in FIG. 4.

FIG. 4. This stepwise process leads to increased refinery profits in a matter of months.
FIG. 4. This stepwise process leads to increased refinery profits in a matter of months.

 

Step 1: Create a segregated paraffinic HRC gasoline pool. Aggregate the paraffinic streams to isolate them from blendstocks that contain significant aromatics and olefins. Reformate and light catalytic gasoline (which cannot be included in the HRC pool) can often blend to make a premium grade. This segregation saves any alkylate and isomerate for the HRC pool. The authors’ company can help create the optimal recipes for this step. Due to ethanol octane synergy, this step alone can lower gasoline production costs by $1/bbl of gasoline.

Step 2: Add aromatic amines to the HRC gasoline. This step further increases the octane available for gasoline blending of paraffinic low-RVP heavy naphtha, which leads to Step 3.

Step 3: Reduce reformer rate (or severity). Refiners no longer need all the octane produced by the reformer, so it can be cut back. Operators will save on operating costs and increase gasoline yield. If refiners are pushing the reformer hard to produce the octane needed, but drowning in H2, this step can be a lucrative money maker.

Not all refineries are the same. Some need every bit of the H2 they produce. There is an alternative path: Maintain the reformer rate and severity to produce H2 but sell the high-octane reformate for a premium if the local market is right, and/or purchase cheap, low-octane paraffinic naphtha to blend to the HRC pool. This will provide the benefits in Steps 4 and 5.

Step 4: Increase liquid yield. The reformer feed that is not being used can be desulfurized and blended into the HRC gasoline pool. It will capture the ethanol octane synergy like other paraffinic stocks and increase revenue.

Step 5: Blend more butane or adhere to challenging RVP specifications. With reduced reformer operations, fewer low-octane, high RVP byproducts are produced like pentanes. This enables refiners to blend more butane, which is an inexpensive paraffinic and high octane. If a very low Reid vapor pressure (RVP) specification must be reached for reformulated gasoline, reducing naphtha reforming will ease the RVP constraint and will be more cost-effective.

Step 6: Reduce Scope 2 and Scope 3 carbon dioxide (CO2) emissions. When HRC gasoline is produced, the CO2 tailpipe emissions of the product are reduced by 12% on a per mile driven basis. These are Scope 3 emissions. When the reformer operation is reduced, the refinery’s Scope 2 CO2 emissions are reduced, the liquid yield of gasoline is increased and the yield of low-octane, high-RVP light byproducts is decreased. The logical conclusion of HRC gasoline is to shut down the reformer and eliminate the Scope 2 emissions, the operating cost and complexity, and the lost liquid yield.

While this is relatively easy for some refiners and difficult for others, producing HRC gasoline can be stepwise. Future regulations may require reduced Scope 2 and Scope 3 COemissions, and producing HRC gasoline gets plant operators started in this direction. While there are real economic benefits to reducing reformer severity, marketing and sales departments will be able to sell lower COtailpipe emissions to drivers who are not willing to part from their gasoline-powered cars and trucks.

Step 7: Eliminate octane giveaway. If a facility is producing HRC gasoline, it will have a high-octane blend tank available with aromatic amines. Refiners can blend to recipes that are just below the octane specification, and when the octane results for that batch are available, aromatic amines can be added to the tank to achieve the correct specifications. Note: This option has not been factored into the authors’ company’s economics, but it would provide additional revenue.

Step 8: Generate sulfur and benzene credits. The cost of sulfur credits has significantly increased since some refiners cannot desulfurize their FCCU gasoline low enough without losing needed olefin octane. HRC gasoline eliminates this concern. Refiners can desulfurize the FCCU gasoline to zero olefins and expand the HRC gasoline pool. Ethanol octane synergy and aromatic amines will economically make up the olefin octane.

HRC gasoline contains much lower benzene because high aromatics stocks are rejected from the HRC blending pool. As the reformer is gradually cut back and ultimately shut down, the benzene in the total gasoline pool continues to decline—benzene credit buyers become sellers.

Health and environmental benefits: Looking to the future

HRC gasoline has 12% lower COemissions on a per mile driven basis. As the technology is accepted, the opportunity to manufacture paraffinic renewable gasoline stocks will further lower COemissions. Why is this important? According to the Fuels Institute, even if all light duty vehicles in the U.S. are zero-emissions vehicles by 2025, the inventory of gasoline-powered vehicles in the U.S. will still be at least 40% by 2050. HRC gasolines are drop-in, do not require engine modifications and adhere to all existing U.S. regulations.

The authors’ company is an early leader in the commercialization process for this technology. The first commercial demonstration of HRC gasoline will be in H1 2024. The authors expect to have two ongoing commercial producers by 2025. HP

The Authors

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