Recently, our laboratory has developed a zeolite-templated synthesis route to microporous three-dimensional (3D) graphene-like carbons via lanthanum-catalyzed carbonization of ethylene. In the present work, we optimized the ethylene carbonization conditions for a zeolite X template, using an inexpensive Ca2+-ion catalyst instead of La3+-ion catalyst. This synthesis gave a high carbon yield based on the template pore volume, and exhibited no significant amount of carbon deposition on the external surfaces. Single crystal X-ray diffraction analysis indicated that the carbon had 3D graphene-or nanotube-like frameworks along the surface of the zeolite pore walls, similar to the case of La3+ catalyst. With a 70-g batch of carbon synthesis, we demonstrated the potential of this synthesis route for large-scale production that would bring about a wide range of practical applications. (C) 2017 Elsevier Ltd. All rights reserved.