Dimethyl ether synthesis

Yield:115-10-6 99%

Reaction Conditions:

NaPZSM-5 in water at 250; under 7600.51 Torr;Product distribution / selectivity;

Steps:

1; 2; 3

Example 1; 300 liters of an NaPZSM-5 catalyst was loaded into a fixed-bed reactor. In this state, the catalyst was pre-treated at 400°C for 1 hour while nitrogen was supplied at a flow rate of 18.5 NmVmin, after which the temperature of the reactor was set to 250°C. Subsequently, hydrous methanol containing 20 mol% of water was supplied as a feedstock under conditions of reaction pressure of 10 atm and reaction temperature of 250°C, and was combined with a recycling stream and thus passed through the catalyst bed at LHSV of 5-10 h^"1.The reaction product (DME, water, unreacted MeOH) discharged from the reactor was transferred into a single separation column. The operation conditions of the single separation column were set as follows, that is, the number of total trays was 56, the pressure of the top tray was about 10 kg/cm², the temperature at the bottom of the column was about184°C, and the temperature at the top of the column was about 48°C. After the feed-in to tray36, the dimethyl ether product from the overhead stream, water from the bottom of the column, and recycled methanol (purity: 98% or more) from fray 9 were withdrawn. The purity of the discharged recycled methanol was 98% or more.The flow rates and the amounts of methanol, dimethyl ether and water of respective streams in FIG. 2 are shown in Table 1 below. As such, single-pass conversion of methanol passing through the reactor was about 80%, and total conversion and yield, including recycling, were about 99% or more (side-reaction product: less than 1%, that is, selectivity: 99% or more).; Example 2; 300 liters of an NaPZSM-5 catalyst was loaded into a fixed bed reactor. In this state, the catalyst was pre-treated at 400°C for 1 hour while nitrogen was supplied at a flow rate of 18.5 Nm³/min, after which the temperature of the reactor was set to 250°C. Subsequently, hydrous methanol containing 20 mol% of water was supplied as a feedstock under conditions of reaction pressure of 10 atm and reaction temperature of 250°C, and was combined with a recycling stream, and thus passed through the catalyst bed at LHSV of 5-10 h^"1.The reaction product (DME, water, unreacted MeOH), discharged from the reactor, was transferred into a single separation column. The operation conditions of the single separation column were set as follows, that is, the number of total trays was 56, the pressure of the top tray was about 10 kg/cm², the temperature at the bottom of the column was about184°C, and the temperature at the top of the column was about 48°C. After the feed-in to tray34, the dimethyl ether product from the overhead stream, water from the bottom of the column, and a mixture of water/methanol (methanol: about 91%, water: 7%) from tray 43 were withdrawn, and the methanol containing water was recycled to a feed surge drum.The flow rates and the amounts of methanol, dimethyl ether and water of respective streams in FIG. 3 are shown in Table 2 below. As such, the single-pass conversion of methanol passing through the reactor was about 80%, and the total conversion and yield, including recycling, were about 99% or more (side-reaction product: less than 1%, that is, selectivity: 99% or more).TABLE 2; Example 3; 300 liters of an NaPZSM-5 catalyst was loaded into a fixed-bed reactor. In this state, the catalyst was pre-treated at 400°C for 1 hour while nitrogen was supplied at a flow rate of 18.5 NnrVmin, after which the temperature of the reactor was set to 250⁰C. Subsequently, hydrous methanol containing 20 mol% of water was supplied as a feedstock under conditions of reaction pressure of 10 atm and reaction temperature of 250°C, and was combined with a recycling stream and thus passed through the catalyst bed at LHSV of 5-10 h^"1.The reaction product (DME, water, unreacted MeOH, 10 kg/cm², near 300⁰C), discharged from the reactor, was in a gaseous phase of about 170~180°C after heat exchange, and was fed into a flash drum before being transferred into a single separation column. Through the flash drum, the temperature was decreased to about 153°C, and partial condensation occurred. About 20% by the mass ratio of the flash drum feed was condensed to . a liquid phase (water: about 93%, methanol: about 6.6%), and 50% thereof was recycled to the feed surge drum, and the residual condensate and the flash overhead gas were separately supplied into the single separation column. The single separation column was composed of a total of 56 trays, the pressure of the top tray was about 10 kg/cm², the temperature at the bottom of the column was about 184°C, and the temperature at the top of the column was about 48°C. The flash drum overhead gas was fed into tray 34, and the liquid condensate was fed into tray 36. As in Example 1, the dimethyl ether product from the overhead stream, water from the bottom of the column, and recycled methanol (purity: 98% or more) from tray 9 were withdrawn. The purity of the discharged recycled methanol was 98% or more.The flow rates and the amounts of methanol, dimethyl ether and water of respective streams in FIG. 4 are shown in Table 3 below. As such, the single-pass conversion of methanol passing through the reactor was about 80%, and the total conversion and yield, including recycling, were about 99% or more (side-reaction product: less than 1%, that is, selectivity: 99% or more).

References:

WO2008/26887,2008,A1 Location in patent:Page/Page column 10-13