Methane to Aromatics Aric Von Buettner

Background Current glut (valley) in natural gas prices High BTX product demand North America currently imports benzene to meet demand This enables a sizable opportunity for processes that convert natural gas to benzene that has no sign of becoming smaller

Process Overview and Issues Use natural gas as the feedstock to produce 728 million lb/yr of mixed benzene and toluene Molybdenum catalyst facilitates reaction Can become deactivated due to coking Various byproducts as result of reaction Hydrogen and Naphthalene

Process Flow Diagram Recycle Section Separation Section Reactor Section

Catalyst Research Each group member found catalyst I presented my research on Mo/ZSM-5 After discussion, chose Mo/H-MFI instead

Constraints Constraint Type of constraint Constraint met (Y/N) How? (Design value) Air Pollution Environmental Y Apply for permit Energy Consumption (depletion of natural resource NG) Brief analysis of NG market Cost of chemicals Economic Economic sensitivities Feedstock limited by amount that is produced Product/Feedstock Comparing our use to total production Unit Op Material Compatibility with chemicals Safety Use stainless steel for unit ops

Design Layout and Optimization Used Visio to create initial process flow diagram Later helped rest of group in making initial Aspen model, converging it Optimization of distillation tower

Unit Operations Sizing and Pricing Hydrogen membrane Allowable hydrogen flow rate Membrane cost $/ft^2 Change in pressure Hydrogen purity

Products: Benzene and Toluene Economic analysis Chemical costing Products: Benzene and Toluene Naphthalene Purge fuel use

Alternative catalysts Design Alternatives Mo/ZSM-5 Mo/MCM-22 Alternative catalysts 5% of stream coming out of hydrogen membrane Purge Burn entire vent stream Vent Mo/H-MFI-B catalyst 1% purge stream Separate aromatics from vent stream Base case

Safety and Risk Management Heat Exchangers Reactor Distillation tower Safety issues Large Temperature deviations from norm Risks Management: Adjusting cold or hot stream flow Temperature and Pressure deviations HTFA Risk Management: Use stainless steel, lower/raise heating/cooling and feed streams, Leaks Obstruction of feed stream Risk Management: Install level alarm and feed flow-rate meter

HAZOP Analysis Table Helpful tool in analyzing the risks with each unit op, along with how to make them safer Example: Unit Op Guideword Deviation Causes Consequences Action required Distillation tower Utility failure Failure Power to reboiler stopped Insufficient reheating resulting in impure bottoms product Install temp. sensor

Broader Impacts / Contemporary Issues Job Creation from methane development CO2 emissions contributing to global greenhouse effect Texas state incentives for chemical plants

Questions?