The technological prospects of repurposing methane steam reformers into ammonia crackers for decarbonized H2 production
Natalia Realpe, Gontzal Lezcano, Shekhar R. Kulkarni, Salvador Sayas, Natalia Morlanés, M.A. Rakib, Ragad Aldilaijan, Bandar Solami, Jorge Gascón, Pedro Castaño
Abstract
The decarbonization of hydrogen production can be accelerated by repurposing existing methane steam reformers into ammonia crackers. Through kinetic modeling, reactor optimization, and process integration, we demonstrated the viability of repurposing industrial reformers into NH 3 crackers using a Co-Ba-Ce extrudate catalyst. First, we combined an improved kinetic rate expression, validated through experiments, with a high-fidelity 2-D model to optimize the operation of a multi-tubular reactor with a fixed capacity of 7000 Nm 3 h −1 . Subsequently, we used heat integration techniques to integrate the reactor with supplementary and separation units. We proved the process energy efficiency to be 65.7% before heat integration and 75.3% for the integrated plant. The integrated, optimized plant results demonstrated the necessity of implementing an adiabatic pre-cracker, an element typically omitted in catalytic NH 3 decomposition techno-economic models. Our findings underscore the importance of real-world constraints and operational aspects in designing and optimizing NH 3 conversion processes. • An ammonia cracker model for a repurposed industrial-scale multitube steam reformer • A refined intrinsic kinetic model for better predictions at high-pressure • Estimation of the most relevant limitations and heat integrations in the unit • Adiabatic pre-cracking can reduce the heat duty of a top-fired furnace by 15%