Patent ID: 8709229

Claim:
A method of operating a hybrid sulfur electrolyzer to generate hydrogen, consisting of: providing an anolyte to an electrolyzer cell, wherein the anolyte has a concentration of sulfur dioxide; and applying current to the electrolyzer cell such that a current density is established; establishing and maintaining a steady state production of hydrogen generation in which a plot of the applied current density on an X-axis of a graph versus the concentration of sulfur dioxide on a Y-axis of the graph is below a boundary line on the graph, wherein the boundary line is linear and extends through an origin of the graph and has a slope of 0.001 in which the X-axis of the graph is current density measured in mA/cm 2 and the Y-axis of the graph is concentration of sulfur dioxide measured in moles of sulfur dioxide per liter of anolyte, wherein the steps of providing an anolyte and applying current occur during the steady state production of the hybrid sulfur electrolyzer, and a start up sequence consisting of: loading anolyte that does not have any concentration of sulfur dioxide into an anolyte tank; impressing a voltage to the electrolyzer cell that is less than that needed to accomplish water electrolysis of hydrogen; heating the electrolyzer cell and the anolyte; slowly adding sulfur dioxide to the anolyte such that anolyte pressure is increased and concentration of sulfur dioxide in the anolyte is increased; obtaining the amount of concentration of the sulfur dioxide in the anolyte by use of the temperature and pressure of the anolyte, wherein the plot of the applied current density on the X-axis of the graph versus the concentration of sulfur dioxide on the Y-axis of the graph is below the boundary line; changing a power supply to the electrolyzer cell to current control once a target current is reached; and decreasing the concentration of sulfur dioxide in the anolyte until the first indication of an increase in voltage in the electrolyzer cell, wherein the decreasing step is performed only if an increase in concentration of sulfur dioxide in the anolyte does not cause a decrease in voltage of the electrolyzer cell.