Redefining Equilibrium in Reforming: The SMR+ Catalyst

Reforming has long been considered a “mature” technology, with steam methane reforming (SMR) at its core. For decades, progress has meant incremental tweaks: better catalysts, smarter operations. Yet the fundamental constraint has remained untouched – the iron grip of chemical equilibrium. Conventional wisdom insists catalysts can speed reactions but never rewrite the rules.

HYCO1’s SMR+ catalyst challenges this paradigm. By engineering the micro-environment at the catalyst surface, SMR+ achieves a new kind of apparent equilibrium, one that shifts performance in ways previously thought impossible. This paper reveals the development of this unique catalyst, the evidence supporting its novel equilibrium behavior, and the benefits it delivers to hydrogen and syngas producers.

The classical framework of reforming relies on three key reactions: steam methane reforming (SMR), water-gas shift (WGS), and dry reforming of methane (DRM). Thermodynamic equilibrium constants for each are considered functions solely of temperature and component partial pressure. In practice, industrial reformers are designed to approach these equilibria, while accepting that complete conversion is unattainable.

In practical terms, this means that once a reformer reaches its operating temperature and pressure, the maximum possible conversion of methane or carbon dioxide is dictated by the ratio of reactants and products at equilibrium. No matter how active the catalyst, the “ceiling” of conversion is fixed by the Gibbs free energy of the reactions. Operators may influence the balance by adjusting temperature or system pressure, but the underlying limit is considered absolute.

For decades, reforming design has been anchored in Gibbs free energy models, bulk-phase equilibrium assumptions, and conventional nickel-based catalysts. These frameworks presume well-mixed gases and a catalyst surface that merely accelerates the path to equilibrium without altering its position. Entire design philosophies (heater sizing, tube metallurgy, steam balance) rest on the principle that catalysts reduce the time to reach equilibrium, not redefine it.

This perspective has been reinforced by the success of conventional nickel catalysts in delivering predictable, reliable performance under well-established operating windows. With enough steam, sufficient residence time, and proper temperature, classical models predict product gas compositions with remarkable accuracy, cementing the belief that equilibrium is a fixed boundary, not a variable to be engineered.

Yet this belief leaves unchallenged an important simplification: that equilibrium is always bulk equilibrium. In reality, equilibrium constants describe the relationship of partial pressures, not total pressure, and the local partial pressure environment at a catalyst surface can differ dramatically from that of the bulk gas. This distinction has been acknowledged academically but often dismissed as a second-order effect in large industrial units.

It is precisely this overlooked distinction that SMR+ is built to exploit. SMR+ does not simply operate within the traditional equilibrium framework, it reshapes it. By engineering the near-surface environment and altering how reactants and products interact at the catalyst surface, SMR+ redefines the limits of reforming. What has long been treated as a fixed ceiling, under the right surface conditions, can be raised. This is not a violation of thermodynamics, but a re-expression of where equilibrium resides in a flowing system, and SMR+ is designed to operate precisely within that space.

SMR+ is therefore an iconoclast: a technology that shatters long-held reforming orthodoxy by proving that equilibrium, once thought immovable, can shift in practice. It is here, at the interface of bulk gas and catalytic surface, that SMR+ overturns the old assumptions and delivers results once thought unattainable.

Equilibrium isn’t just temperature and pressure - it’s about the partial pressures of individual species. When engineers cite conditions like “900 °C and 25 bar,” they’re really describing a ratio of reactant and product partial pressures that satisfy the Gibbs free energy minimum. But here’s the nuance: those ratios apply to the bulk gas, not necessarily to the catalyst surface. Near the surface, adsorption, diffusion, and reaction rates can create a microenvironment where conditions differ dramatically from the bulk gas. If the local ratios deviate, reactions will continue at the surface even when the bulk appears to be ‘at equilibrium.’ SMR+ turns this subtlety into an advantage, deliberately shaping the near-surface environment to push conversion beyond traditional limits.

In plug flow reactors, such as reformer tubes, this difference between bulk and surface conditions becomes magnified. Products generated at the catalyst surface are continuously swept downstream, while the surface is replenished by fresh reactants diffusing from the gas phase. The immediate environment of the catalyst active sites is therefore not static: it is a constantly shifting interface where local partial pressures differ substantially from the average bulk composition.

This dynamic has a profound consequence. If carbon monoxide and hydrogen are removed from the surface as soon as they are formed, the apparent equilibrium at the catalyst interface resets in favor of further forward reaction. According to Le Châtelier’s principle, the system responds to the depletion of products by accelerating their regeneration. The result is a persistent micro-equilibrium at the catalyst surface that can lie well beyond what bulk equilibrium calculations predict.

SMR+ is designed to take advantage of this effect. The NiMgO solid solution creates a surface that not only binds CO₂ strongly but also maintains a high local coverage of oxidizing species. This ensures that methane fragments arriving at the surface see an environment rich in reactants (CO₂, H₂O, and oxygen from lattice vacancies), while the products they form are efficiently carried away by the plug flow of gas through the tube. SMR+ intentionally amplifies the divergence between surface and bulk conditions, forcing the reaction to proceed well beyond the limits defined by classical equilibrium.

Critically, this does not represent a violation of thermodynamics. The global equilibrium constant at a given temperature and pressure remains fixed. What changes is the path that system takes to approach that equilibrium in a flowing reactor. At the catalyst surface – where reactants arrive, products depart, and the gas is continually renewed – the local driving forces can differ from the bulk conditions by design.

This recognition reframes how reforming should be understood. Rather than treating equilibrium as a hard ceiling applied uniformly across the reactor, SMR+ highlights that surface equilibria under plug flow can be deliberately shifted to achieve higher effective conversions. It is in this subtle but powerful way that SMR+ redefines what reformers can deliver, taking advantage of the physics of flow and the chemistry of surfaces simultaneously.

Figure 1. SMR+ achieves higher CH₄ conversion than classical equilibrium predicts (Sample Case Depicted).

SMR+ is built upon a fully sintered NiMgO solid solution catalyst, a structure fundamentally different from conventional nickel-on-carrier designs. Traditional reforming catalysts disperse metallic nickel particles across supports like alumina, modified alumina, or similar alternatives, where the exposed Ni surface sites catalyze methane activation. While effective, these systems suffer from well-known drawbacks: nickel sintering under high heat, carbon deposition from methane cracking, and the need for high steam ratios to suppress coking and enhance gasification.

By contrast, SMR+ embeds nickel within a magnesium oxide lattice, forming a stable solid solution that creates a new type of active surface. This surface is inherently CO₂-philic, it attracts and retains carbon dioxide molecules more strongly than conventional catalysts. Rather than acting as a passive diluent, CO₂ becomes a functional promoter directly involved in the chemistry at the surface.

This CO₂-affinity drives three simultaneous benefits:

1. Self-cleaning surface: Oxygen from CO₂ adsorbates (and to a lesser extent H₂O) reacts with nascent carbon as soon as it forms on Ni sites. Instead of growing into graphitic coke, carbon is converted rapidly to CO, preventing fouling.
2. Suppression of Water-Gas Shift competition: Preferential engagement of CO₂ at the catalyst surface allows it to outcompete H₂O for oxygen exchange sites. This reduces the extent to which CO and H₂O are driven through the WGS reaction and instead channels CO₂ into direct reforming pathways.
3. Enhanced driving force for reforming: By enriching the local environment with oxidizing species, the NiMgO surface creates conditions where hydrocarbon fragments encounter abundant oxygen acceptors. Combined with plug flow removal of products, this shifts the apparent surface equilibrium toward higher conversions.

In practical terms, SMR+ uses CO₂ not as a burden to be managed, but as a reactive partner. This is a major departure from conventional reforming strategy, which relies on large excesses of steam as a defensive measure against carbon formation. Steam is effective but carries an energy penalty in generation, superheating, and condensation. By replacing “steam as insurance” with “CO₂ as promoter,” SMR+ redefines the cost and efficiency equation of reforming.

This is where the catalyst stops being a passive participant in equilibrium and becomes an iconoclast in design philosophy: deliberately engineering the surface microenvironment to alter reaction pathways and reshape how equilibrium is expressed under operating conditions.

The unique behavior of SMR+ could not be captured by conventional kinetic approaches. Standard Langmuir–Hinshelwood formulations assume that rates are controlled by competitive adsorption of reactants on identical active sites, and that the equilibrium ceiling for conversion is dictated solely by bulk gas composition. Likewise, simple power-law fits can track trends within a narrow dataset but fail when extended beyond the conditions under which they were calibrated. In both cases, the models inherently assume that the surface environment is a reflection of the bulk gas, an assumption that does not hold for SMR+.

SMR+ experimental data consistently showed conversions that surpassed bulk equilibrium expectations, most dramatically in dry reforming (DRM) and co-reforming mixtures where CO₂ is abundant. This was not a statistical anomaly: repeated trials, pilot runs, and eventually commercial demonstrations (e.g., Agra Energy’s SAF plant) confirmed that the observed conversions were real, repeatable, and stable. The challenge, therefore, was not to question the data, but to evolve the kinetic framework to explain it.

SMR+ kinetics were restructured to explicitly include the effects of surface equilibria. Three key elements distinguish this formulation from classical approaches:

• Surface oxygen availability (from adsorbed CO₂ and H₂O, as well as from lattice oxygen vacancies in NiMgO) becomes a direct rate-scaling factor. Reaction rates increase when surface oxidants are plentiful, enabling hydrocarbon fragments to be consumed before they polymerize into coke.
• Partial pressure differentials between surface and bulk are accounted for. Because products (CO, H₂) are continuously swept away in plug flow, their local concentrations at the surface remain lower than bulk averages, sustaining forward reaction rates in accordance with Le Châtelier’s principle.
• Reaction pathways are broadened to reflect the unique chemistry of the NiMgO interface, where CO₂ can directly oxidize carbonaceous intermediates.

The resulting framework is not a rejection of thermodynamics but an extension of it into the catalytic microenvironment. By recognizing that the surface is its own equilibrating system, the model reproduces observed conversions with high fidelity. What classical models interpreted as “beyond equilibrium” is redefined as the outcome of a surface-driven micro-equilibrium operating in tandem with bulk flow.

Most importantly, SMR+ breaks the longstanding dependence on high steam levels. In conventional reforming, excess steam is treated as nonnegotiable: both a coke suppressant and a stabilizing buffer. SMR+ removes that constraint. Steam becomes a knob to adjust product ratios and thermal balance, not a fixed requirement for safe operation. CO₂ simultaneously shifts from being a burden to a productive oxidant within the chemistry. This reframing is central to the efficiency gains and flexibility observed in SMR+.

A defining demonstration of SMR+ performance comes from Agra Energy’s SAF plant near Green Bay, Wisconsin. Here, HYCO1’s SMR+ catalyst is deployed at commercial scale and validated by independent engineering review:

• Consistently high CO₂ conversion, limited primarily by methane availability.
• Stable operation for more than 3,000 hours, with no evidence of deactivation or abnormal pressure drop.
• Reliable operation at ~2:1 steam-to-carbon (S:C) ratio, far below the ~3:1 threshold conventional catalysts demand to avoid coking.
• Tight H₂:CO ratio control at ~2.2, ideal for Fischer–Tropsch synthesis, achieved without equipment modification.
• Confirmed TRL-9 performance, proving commercial readiness in sustained production environments. (Figures 2–4)

Figure 2. SMR+ performance at Agra. Data points show SMR+ product gas composition, indicating ~85%+ CO₂ conversion and near-complete CH₄ conversion, benchmarked against traditional catalyst baselines.

Figure 3. SMR+ operating data showing a stable S:C ratio near ~2.0 over long term operation at Agra. Dashed line indicates the ~3.0 S:C minimum typically required for traditional Ni catalysts.

Figure 4. SMR+ operating data showing stable H₂:CO ratio control at ~2.2, suitable for Fischer–Tropsch synthesis.

Within HYCO1, operators observed a consistent and measurable conversion beyond what bulk equilibrium would predict, a phenomenon they began referring to as the “bonus reaction.” This describes the additional CO₂ and CH₄ conversion that appears once surface-driven equilibria begin to dominate over bulk gas limits. Mass balances have confirmed that this is not measurement noise or accounting error, but a repeatable operating feature of SMR+. The value of the bonus reaction is straightforward: higher effective conversion, lower methane slip, deeper CO₂ utilization, and improved yield without increasing temperature or steam. It reflects an operational manifestation of surface equilibria effects, where SMR+ enables reactions to proceed further than classical, well mixed models allow.

Plots of Approach-to-Equilibrium (ATE) for SMR+ sometimes show values below zero, which has raised objections. It is essential to clarify that this is an 'Apparent ATE’, a diagnostic indicator of surface-driven kinetics, not a literal thermodynamic violation. SMR+ surfaces operate closer to equilibrium than bulk outlet compositions suggest, because products are continually removed and reactants replenished. Thus, negative ATE values should be interpreted as evidence of highly favorable surface equilibria in plug flow, rather than as impossible thermodynamic outcomes. (see Figure 5)

Figure 5. Apparent ATE (A‑ATE) reveals the contribution of surface-dominated equilibria, distinguishing SMR+ behavior from traditional catalyst deactivation profiles.

• More hydrogen, less steam: higher H₂ yield at ~2:1 S:C ratios.
• Lower fired duty: reduced energy input to reach target conversion.
• Coke immunity: CO₂ surface activity gasifies nascent carbon.
• Rapid startup: activity on heat-up, no extended hydrogen pre-reduction.
• Flexible operation: effective in SMR, DRM, and co-reforming.
• CO₂ as feedstock: emissions converted to valuable syngas.

The implications of SMR+ extend well beyond a single plant or flow scheme. For decades, reforming has been locked into the same design paradigm: nickel on alumina, high steam ratios, and equilibrium treated as a ceiling. SMR+ breaks that mold. It demonstrates that equilibrium can be reinterpreted, kinetics can be reformulated, and CO₂ can be revalorized as a promoter rather than a liability.

This opens the door to a new generation of syngas systems:

• Smaller furnaces with lower fired duty.
• Processes that consume CO₂ rather than venting it.
• Configurations that integrate seamlessly with downstream SAF, methanol, or ammonia synthesis.

Most importantly, SMR+ serves as an iconoclast for reforming design philosophy: proving that the old rules are not absolute, and that by re-engineering the catalyst surface itself, the boundaries of performance can be pushed further than once believed.

• Reformer design flexibility with respect to operating pressures, optimizing compression work and improving efficiency.
• Lower S:C ratios cut steam generation duty and OPEX, while also simplifying water logistics.
• H₂:CO ratios can be tuned without auxiliary reactors, enabling direct integration with downstream FT, methanol, or oxo processes.
• Lower carbon intensity positions operators to meet ESG and regulatory demands while improving economic returns.
• Transforms CO₂ into a usable asset, enabling co-reforming strategies that traditional catalysts cannot deliver.

SMR+ represents a genuine breakthrough in reforming catalysis. It does not defy thermodynamics, but it redefines how equilibrium is achieved at the surface. By creating a new micro-equilibrium, SMR+ delivers conversions, yields, and flexibility that conventional catalysts cannot match.

The message is clear: equilibrium is not just a bulk property, it is something a catalyst can shape. In a sector long considered mature, SMR+ proves innovation is still very much alive.