Decarbonisation Technology May 2022 Issue

Repurposing existing process units to reduce CO 2 emissions Converting an existing hydrotreater or naphtha reformer to a Methaformer can reduce both CO 2 emissions and energy costs

Stephen Sims New Gas Technologies Synthesis (NGTS) Meritxell Vila MERYT Catalyst and Innovation

M ethaforming is a lower-cost alternative for upgrading naphtha to gasoline blendstock in a one-step process that reduces energy costs and CO 2 emissions. An existing hydrotreater or naphtha reformer can be converted to a Methaformer at a low cost and reduce CO 2 emissions by 0.5t CO 2 /t naphtha. For a typical 20K BPD (860K tpa) process unit, the conversion cost will be <$20 million with CO 2 emissions reductions of 430K tpa, worth $22 million/year at $50/t of CO 2 or a whopping $62 million/year at the current $140/T in California (CA). The conversion may be of either the hydrotreater or the reformer. For the hydrotreater, the main cost is for two reactors (one on-stream while the other is regenerated), and for a semi-regen reformer, the main revisions are piping changes. The CO 2 emissions credits mentioned above are in addition to the underlying Methaformer yield advantage, which is worth $40 million/year compared to a semi-regen reformer (based on US Gulf Coast long-range prices). Methaformer yields are comparable to a semi-regen reformer with isomerisation but without the need for hydrotreating, while ensuring benzene in the product is <1%. Additionally, Methaforming reactively extracts ethylene from fluid catalytic cracker (FCC) dry gas, which from a companion 50K BPD FCC would be worth an additional $10 million/year in upgrading the ethylene from fuel gas to gasoline. CO 2 emissions reduction The estimation of CO 2 emissions savings is based on the California Low Carbon Fuel Standard (LCFS) methodology. Methaforming

is inherently more energy efficient, as it does not require the reheat furnaces as in a reformer or any energy for a naphtha hydrotreater. This accounts for 20% of the emission credits, equivalent to 0.1t CO 2 /t naphtha. Then for ethanol co-feed, the hydrocarbon portion that becomes gasoline, the CO 2 emissions due to combustion in the automobile are offset by the CO 2 absorption in growing the crops for the ethanol. This is why blending ethanol into gasoline is attractive. In essence, using ethanol as the co-feed in the Methaformer enables the environmental benefit of blending more ethanol into gasoline without hitting the blend wall. While still following the LCFS methodology, the mechanism for CO 2 emissions reduction when ethylene is used as a co-feed is totally different. In a common refinery configuration, ethylene in the FCC dry gas is used as refinery fuel gas. When the ethylene is reactively extracted at the Methaformer, its heating value is replaced with natural gas. This has two benefits. First, the hydrogen/carbon ratio for natural gas is twice that for ethylene. More of the BTUs come from hydrogen than carbon. Second, the CO 2 emissions allocated to the ethylene include a share of the emissions from the entire value chain from crude into refining through the FCC, allocated based on contained heating value. This is much more than the CO 2 emissions from natural gas production. In this way, in essence, natural gas is converted directly into gasoline. Methaforming economics vs conventional technology Methaforming is a one-step process (see Figure 1 ). Naphtha and ethanol/methanol or