How to Provide a column data inside a replace method in T-SQL

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SQL-Server-2008R2

Hi,
I'm writing a USP to clean a column using REPLACE() method.
The replace command is:

ALTER PROCEDURE [NetDB].[dbo].[usp_cleanUpProcessForT4]
AS
  BEGIN
  SET NOCOUNT ON
  DECLARE @Command NVARCHAR(MAX)
  SET @command = '
		UPDATE [NetDB].[dbo].[Table4]
		SET [DA_ArticleDetails] = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(DA_ArticleDetails,"||$|| ||$||"," "),"||$||"," ")," ","<>"),"><",""),"<>"," ")'
		BEGIN TRY
		 EXEC(@Command)
		PRINT
		 'Applied rule#1 to 5... Executed Successfully.'
		END TRY
		BEGIN CATCH
			PRINT 'rule#a1 Error'
		SELECT 
		  ERROR_NUMBER() AS ErrorNumber
		  ,ERROR_MESSAGE() AS ErrorMessage;
		END CATCH
END

Here I'm getting the ErrorMessage as

An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or [] are not allowed. Change the alias to a valid name.

What should I do? Please help.